Recently emerged new field of all-dielectric resonant metaphotonics aims at the manipulation of strong optically induced electric and magnetic Mie-type resonances in dielectric and semiconductor nanostructures with relatively high refractive index. Unique advantages of dielectric resonant nanostructures over their metallic counterparts are low dissipative losses and the enhancement of both electric and magnetic fields that provide competitive alternatives for plasmonic structures including optical nanoantennas, efficient biosensors, passive and active metasurfaces, and functional metadevices. This talk will summarize the recent advances in all-dielectric resonant metaphotonics including active nanophotonics as well as the recently emerged fields of biosensing, topological photonics, and nonlinear metasurfaces.

Single-molecule localization microscopy (SMLM) can provide a truly molecular image of complex biological processes. We aimed to better understand how the T cell receptor (TCR) translates antigen binding into intracellular signals on which T cell fate decisions are based. With SMLM and novel analyses, we determined how the spatial organization regulates signal initiation and propagation (Pageon et al. PNAS 2016). We also developed novel FRET sensors to monitor the rate of receptor clustering (Ma et al. Nat Commun 2017) and a sensor that reports membrane charges (Ma et al. Nat Biotech 2017) to understand how biophysical properties of the plasma membrane contribute to TCR signaling. More recently, we developed an improved single molecule microscope that achieves ~2-3 nm localization precisions and thus enables direct distance measurements between membrane proteins.

Quantum entanglement is a special connection between the particles, which enables correlations without interaction. Entangling photons, elementary particles of light, brings the promise of secure communication and ultra-fast quantum computing. Another phenomenon called optical nonlinearity allows interaction between electromagnetic waves of different colours. Bringing the concepts of quantum entanglement and optical nonlinearity together, and integrating them on a chip, opens a way to efficiently generate entangled photons and tune the entanglement.

We report on the experimental and numerical results for the second-harmonic generation spectroscopy by doughnut-shaped cylindrical vector beams of azimuthal and radial polarizations in individual subwavelength AlGaAs particles, which support multipolar Mie resonances at the fundamental and double frequencies. We observe high-Q resonant optical modes associated with bound states in the continuum for the azimuthally polarized pump beam with the record-high efficiency (0.1%) of the up-conversion nonlinear optical process due to a strong electromagnetic field confinement. Our findings provide an important step towards a design of resonant subwavelength all-dielectric nanostructures with tailored efficiencies of nonlinear optical phenomena at the nanoscale.

The spatial filtering of optical signals has been demonstrated previously with metasurface thin-films created from arrays of structured optical elements. We consider the problem of changing the symmetry of their response with changes to the in-plane wave vector and show it can be tailored or even dynamically tuned. Our work is based on a general theory of metasurfaces constructed from non-diffracting arrays of coupled metal particles. We present the optical transfer function of such a metasurface, identify the physical properties essential for asymmetry and demonstrate its behaviour experimentally.

Increasing demand for higher resolution of displays requires techniques achieving contrast tunability of the images. Employing metasurfaces for image contrast manipulation is a growing field of research aiming to address this need. Here, we employed the thermo-optical properties of dielectric metasurfaces to achieve reversible image tuning. It is demonstrated that by fixing the wavelength and employing metasurfaces with sharp resonances, one can control the transmittance of a metasurface, by controlling the temperature. We demonstrated the first made binary thermally tunable image made by metasurfaces and investigated the ability to bring in multiple states of contrast by employing multiple metasurfaces.

Efficiency of optical frequency conversion in quadratic media critically can be increased by spatial modulation of the nonlinear optical response of the materials vis Quasi Phase Matching (QPM). The QPM structures, also known as the nonlinear photonic crystals, offer a variety of novel properties and functionalities that cannot be obtained in uniform nonlinear crystals. In particular the 3-dimensional modulation of nonlinearity allows one to realize the so-called nonlinear volume holograms which extends the concept of volume holography to nonlinear optics. When illuminated by fundamental beam, the nonlinear hologram gives rise to a wave at different frequency having complex intensity distribution following the transverse structure of the hologram itself. In this work we present formation of various types of nonlinear volume holograms in ferroelectric crystals by using unique all-optical domain inversion technique and demonstrate their application in optical wave-shaping.

Periodic arrays of magnetic microtraps patterned on a magnetic film provide a potential complementary tool to conventional optical lattices for trapping ultracold atoms. This paper presents the trapping of rubidium atoms in submicron period triangular and square magnetic lattices at distances down to about 90 nm from an atom chip. The measured trap lifetimes presently range from 0.4 to 2.5 ms and increase approximately linearly with increasing distance from the chip surface. The result represents a significant step towards employing magnetic lattices for quantum tunnelling experiments to simulate condensed matter and many- body phenomena in lattices with non-trivial geometry.

Bose-Einstein condensates provide a versatile tool for examining analogies to other physical systems. Here we use Bose-Einstein condensates in an arbitrary 2D potential patterned by a spatial light modulator with spin-orbit coupling to test the hypothesis that on a diamond lattice spin-orbit coupling can induce a flat dispersion curve. This flat band is supposed to give rise to compact localised states in which the particles are localised to a subset of lattice sites.

Time crystals are an exotic form of quantum matter in which a periodically driven quantum many-body system spontaneously self-organizes its motion and repeats itself in time, rather than in space, with a period longer than the driving period, allowing the periodic structure to resist fluctuations and to persist for long periods of time. Here, we report progress towards realizing discrete time crystals using a Bose-Einstein condensate of potassium-39 atoms bouncing on an oscillating mirror.

Atom-Trap Trace-Analysis is a technique aimed at a measuring the relative abundance of exceedingly rare noble gas radio-isotopes, for the purposes of accurate dating of water and ice. In a facility jointly created by CSIRO, Griffith and Adelaide Universities, we use laser cooling and trapping to perform isotopic separation based on the isotopic dependence of atomic energy levels. The facility is currently undergoing construction but has already been shown to be able to produce metastable Ne and Ar, which has been subsequently laser cooled and trapped. When combined with an existing gas separation facility at the CSIRO Waite facility, which efficiently extracts pure noble gases from that dissolved in water or ice samples, we should be in a position to start measuring the age of real-world samples in the early part of 2020. I will also discuss our experimental results on new efficient and efficacious laser-based approaches to produce metastable atoms.

III-V compound semiconductor nanowires have drawn much attention as nanoscale light sources for integrated photonics due to their nanoscale size, good optical properties and strain relaxation feature enabling the monolithic growth on lattice mismatched substrates. In this talk, we present the study of the selective area epitaxy growth of InGaAs/InP quantum well nanowire array by metalorganic chemical vapour deposition (MOCVD) technique, and the demonstration of both single and array nanowire LEDs with an in-depth investigation of their geometry related device properties.

The group of (100)-grown III-V-semiconductors, have recently been presented as promising materials for second harmonic generation (SHG) at the nanoscale. However, major obstacles is the limited control over directionality of the SH emission and especially zero forward/backward radiation. In this work, we provide a solution to this problem by presenting the first SHG nanoantennas made from (111)-GaAs embedded in a low index material. Our nanoantennas show superior forward directionality compared to their (100)-counterparts. Most importantly, via (111)-nanoantennas one can manipulate the SHG radiation pattern by changing the pump polarization without affecting the linear properties and the total nonlinear conversion efficiency.

Optical angular momentum provides a useful dimension for data multiplexing and quantum entanglement. However, the demultiplexing of optical angular momentum is often performed by complex bulk optics and multiple detectors. Here we demonstrate that chiral plasmonic electrodes can be used to selectively detect optical angular momentum in a compact and integrated format. We demonstrate direct detection of photon spin and investigate methods for the detection of orbital angular momentum.

Here, we investigate the multipolar second-harmonic switch between forward and backward directions from GaAs nanoantennas. Based on the peculiar nonlinearities of zinc-blende semiconductors, we demonstrate both theoretically and experimentally unidirectional nonlinear emission routing and switching via pump polarization control. Our results offer exciting opportunities for nonlinear nanophotonics technologies, such as nanoscale light routing elements, nonlinear light sources, nonlinear imaging, multifunctional flat optical elements.

Liquid biopsies have garnered significant attention due to their capability of providing a snapshot on the molecular landscape of cancer for individualized disease management. However, the achievement of liquid biopsies is challenging due to the rare amount of cancer-relevant target biomolecules against an abundant background of non-biotargets. To overcome this technical hurdle, we have proposed and utilized surface-enhanced Raman spectroscopy (SERS) as an analytical tool for the liquid biopsy application, due to the ultra-sensitivity and multiplexing capability of SERS. As plasmonic materials are the most common Raman signal amplifiers, advances in plasmonic nanomaterials play critical roles in facilitating SERS applications. We thus have developed few strategies to engineer the functional plasmoinc nanomaterials for SERS based liquid biopsy application. A series of plasmonic nanostructures have been synthesized and applied for both ctDNA mutants and exosomes in patient's plasma.

The Photon Factory has recently made significant progress in evaluating complex biomaterials (e.g. milk, skin, bone) at a compositional level. The key tool is fibre-delivered spectroscopy, including fluorescence and Raman scattering. This presentation will discuss recent advances.

We have studied the bandwidth of atomic magnetometers based on nonlinear magneto-optical rotation (NMOR). We demonstrated broadband, high-bandwidth magnetic field measurements from DC up to 100kHz with two different techniques. The first technique measures the instantaneous phase evolution of the optical polarisation rotation in the temporal domain which enabled quantitative measurements of modulated magnetic fields up to 100kHz for a carrier frequency of 30kHz, while the second method employs active feedback techniques to track magnetic field fluctuations up to 100kHz, approximately 2800-fold greater than the passive bandwidth.

We demonstrate the fabrication and characterizations of hybrid lead-silicate glass fibre with intrinsic magnetic sensitivity. The fibre was doped with micron-sized diamond particles at a well-defined 13-µm ring-shape interface. By coupling excitation laser from the input end of a 30-cm-length fibre sample, we observed the ensemble nitrogen-vacancy (NV) centres along the fibre showed strong fluorescence intensities. Moreover, efficient read-out contrast in the optically detected magnetic resonance (ODMR) measurements was obtained from the side of fibre. We also observed the guidance of NV fluorescence emissions to fibre propagating modes, opening the possibility of remote magnetometry via the hybrid diamond-glass optical fibre system.

In this paper, we report the response of Cobalt-60 gamma irradiation on Photonic Crystal Fibre Bragg gratings (PCF-FBGs) and standard commercial FBGs (STD-FBGs). Optical measurements were performed to determine the shift of the Bragg wavelength as a function of accumulated dose and relaxation time. To simulate real time conditions of a radiation dosimeter, the FBGs are examined through three consecutive radiation stages followed by very limited recovery times. We were able to obtain a Bragg wavelength shift with both sets of FBGs. The PCF-FBGs response included strong recovery after each irradiation compared to the STD-FBGs. This makes the PCF-FBGs strong candidates as optical fibre FBG sensors in the area of radiation dosimetry.

In this paper we demonstrate high grating strength (Κ> 4 cm-1) grating inscription for the underwater DFB fiber laser sensing applications using Coherent Braggstar excimer KrF laser. Developed FPGA-controlled stepping recording system allows for the recording of long (up to 52mm) gratings with error compensation, chirping, apodisation for side-lobe suppression and at arbitrary high exposures. Our recording arrangement included a phase mask lens imaging system, a PI stepping translation stage N-563,360 and an auxiliary Michelson interferometer for the translation stage error tracking. Batch recording of fibre gratings was also proposed and demonstrated for low-cost industrial applications.

Certain spider silks, as used in aerial orb webs, are high quality optical micro-fibers. Reduced relative reflectance in the ultra-violet and violet has been reported for such silks. But, this gives no insight into the fraction of the intensity of light that falls on a spider silk that will be backscattered/reflected. We will report comparative results from measurements of the radial silks of four orb web weaving spider species. Combining the results of photoreflectance measurements and optical surface profiling studies shows how the size and geometry impact potential visibility and uncover other important optical materials properties.

Fluorescence images approaching sub-micron resolution are formed in thin nanocrystalline phosphor films. The images are created with UV exposure of the films under chrome-coated quartz masks. The UV light locally changes the valence state of the samarium ions in the nanocrystalline phosphors to activate fluorescence properties. The red fluorescence images are then read-out with blue-violet light. With an imaging resolution approaching the diffraction limit, this technology has potential for anti-counterfeiting labelling or optical data storage applications.

Now at UNSW since 2005, Prof Ladouceur research effort focusses on the development of novel optical sensing technologies with potential applications in the fields of distributed sensors, monolithic Q-switched lasers and brain/machine interface.

Organic fluorophores with π-conjugated scaffolds are important because of their interesting optoelectronical properties. We have focused on the photophysics of a less explored class of cross-conjugated Y-shaped enediynes (one double and two triple bonds). Here we present the photophysical properties of such enediynes which show interesting photophysical properties that include dual emissions from locally excited (LE) and intramolecular charge transfer (ICT) states and ring size dependent aggregate fluorescence in non-aqueous media. The dyes also show prominent aggregate fluorescence in mixed-aqueous solvents, and solid powder form. We further show that the solid state fluorescence can be reversibly switched multiple of cycles by external stimuli, highlighting their potential applications in solid states. The enediynes with push-pull electronic substituents/moieties exhibit high contrast fluorescence color switching upon continuous photon illumination.

Optical sensors based on chalcogenide glass fibers transparent in the mid infrared (MIR) spectral range from 2 to 16 µm (4000 to 625 cm-1) have been developed in order to analyse biological and chemical samples. These sensors are based on the Fiber Evanescent Wave Spectroscopy (FEWS) principle. Indeed, most of the molecules have their functional groups absorption bands in the mid infrared region and the fibers are able to detect the characteristic vibrations these of molecules. Tellurium fibers in the Te-Ge-Se and Te-Ge-AgI glassy systems have been developed in the frame of large-scale projects such the DARWIN mission in order to permit the detection of CO2 at 15 µm. Finally, due to the growing need for sensors able to detect diseases in the medical domain or polluting molecules in the environment area leads us to the detection of molecules such as benzene, chloroform, lipids and sugars.

This paper reports on a multi-point optical fiber pressure sensor using fiber Bragg gratings (FBGs) written on an exposed core optical fiber (ECF) by femtosecond laser. The pressure sensing elements were constructed as Fabry-Perot (FP) interferometers of different cavity lengths using pairs of FBGs with identical resonant wavelength. In this fashion an interference pattern was formed within the FBG bandwidth with much narrower fringes, leading to better detection limit. Fast Fourier transform (FFT) was used to calculate the phase change of the FP interference pattern with respect to applied pressure. The pressure sensitivity was proportional to the cavity FP cavity length, and reached -0.672 rad/MPa for the case of FP with 9 mm cavity length. The proposed sensor has potential to measure pressure at very high temperature thanks to its single material configuration.

Nanoscale thermometry of biological systems offers new insights into cell metabolism at a sub-cellular scale. Currently, there is no way in which we can achieve high resolution temperature sensing on these systems without the use of foreign materials such as biological markers. Using rare-earth doped tellurite glass as a platform for thermometry, we report micron scale temperature sensing via confocal scanning microscopy. By mapping the fluorescence intensity, we resolve the edge of a water droplet with a pixel width of 1μm and measure a net temperature change of 7.04K with a sensitivity of 0.12K. These results pave the way for 'marker free' sub-micron temperature sensing in biological systems.

Conventional sensing technologies cannot distinguish multiple sources of water or humidity without employing numerous sensors. A distributed approach can provide humidity mapping and liquid-depth measurements. A long-range distributed humidity sensor is proposed and will be demonstrated with ultra-low-cost sensing elements along a microstructured sensing fiber based on exposed-core fiber, humidity-sensitive polyelectrolyte multilayer coatings, and coherent optical frequency-domain reflectometry. The sensing mechanism involves monitoring back-reflected optical signals created by changes in the local reflectivity due to water-induced reduction in the local refractive-index of the coating. An advanced segmented-coating strategy ensures low propagation-loss of light, material cost savings, and maximized sensing range.

There has been a major upsurge in activity to realise optical imaging at depth. This is a burgeoning requirement and holds promise for moving towards new understanding of disease and biological function. I will describe new advances in light sheet imaging and wide field multiphoton imaging that use advanced photonics beam shaping to address these issues. This will include the use of propagation invariant Bessel and Airy light fields and the use of temporal focusing for multiphoton excitation combined with single pixel detection.

Adaptive Optics (AO) has become a standard technology in modern ground-based astronomical telescopes, providing an order of magnitude gains in angular resolution and sensitivity. Every major observatory is equipped with first or second generation AO, often using laser guide stars. The European Southern Observatory (ESO), together with an consortium made of several European institutes and led by Australia's AAO, has embarked in the construction of MAVIS, a multi-conjugate adaptive optics system for the ground-based 8-m Very Large Telescope (VLT). MAVIS will deliver visible images and integral field spectrograph data with 2-3 times better angular resolution than the Hubble Space Telescope, making it a powerful complement at visible wavelengths to future facilities like the space-based James Webb Space Telescope and the 30 to 40m-class ground-based telescopes currently under construction, that are all targeting primarily near-infrared wavelengths. I will present an overview of the foreseen MAVIS technical capabilities and the exciting science enabled by it.

The availability of nanometer scale fabrication techniques has inspired scientists to investigate subwavelength-structured metamaterials with engineered optical properties. Metamaterial waveguide devices are becoming established as fundamental building blocks for the next generation photonic integrated circuits. Here we present an overview of recent advances in this surging field, including metamaterial fiber-chip couplers, ultra-broadband telecom devices, biosensors and astrophotonic spectral filters. We will review how optical metamaterials will enhance the performance of the next generation of integrated photonic devices and we explore some of the arising challenges encountered in the transition from concept demonstration to viable technology.

For device applications, structural disorder and optical scattering have long been considered annoying and detrimental features that were best avoided or minimized. In this talk, I will show that disorder and complexity can be harnessed for photonic applications, in particular, to provide unique functionalities of photonic devices. We recently developed an on-chip random spectrometer that combines high resolution with small footprint. In addition, we incorporated disorder to a laser to reduce the spatial coherence for free-speckle full-field imaging.

Substantial in vitro and physiological experimental results suggest that similar coherent spin physics might underlie phenomena as varied as the biosensing of magnetic fields in animal navigation and the magnetosensitivity of metabolic reactions related to oxidative stress in cells. If this is correct, organisms might behave, for a short time, as “living quantum sensors” and might be studied and controlled using quantum sensing techniques developed for technological sensors. I will outline our approach towards performing coherent quantum measurements and control on proteins, cells, and organisms in order to understand how they interact with their environment and how physiology is regulated by such interactions. Can coherent spin physics be established – or refuted! – to account for physiologically relevant biosensing phenomena, and be manipulated to technological and therapeutic advantage?

In recent years, superconducting qubits have shown the high fidelity gate operations needed for practical quantum computing, and small qubit devices have already been demonstrated [1]. One outstanding challenge for superconducting qubits is that they interact strongly with microwave photons, but the high noise at microwave frequencies makes it difficult to store and transmit these photons. A solution is to convert the microwave photons into optical photons, where technology for transmitting and storing quantum information is well-developed. Recently, we described a method for performing this up-conversion with rare earth doped crystals [2]. This method uses rare earth ions with a paramagnetic transition resonant with the microwave photon and an electronic transition resonant with the optical photon, placed in both an optical and a microwave cavity, to perform up-conversion. The up-conversion efficiency is proportional to the rare earth ion concentration and the electronic and paramagnetic resonance linewidths. We propose that higher efficiencies can be obtained in crystals stoichiometric in the rare earth. These materials can show magnetic ordering, and, in the ordered regime, macroscopic spin resonances that have the potential for narrow resonance linewidths. I will describe initial studies of stoichiometric crystals for this application, and outline the expected performance in an microwave-to-optical up-converter. [1] R. Barends, J. Kelly, A. Megrant, A. Veitia, D. Sank, E. Jeffrey, T. C. White, J. Mutus, A. G. Fowler, et al., Superconducting quantum circuits at the surface code threshold for fault tolerance, Nature 508, 500 (2014). [2] L. A. Williamson, Y.-H. Chen, and J. J. Longdell, Magneto-Optic Modulator with Unit Quantum Efficiency, Physical Review Letters 113, 203601 (2014).

Latest advances in integrated single-photon detectors offer possibilities for gaining information inside quantum photonic circuits. We introduce a concept and provide experimental evidence for the inline tomographic measurement of multiphoton quantum states, while keeping the transmitted ones undisturbed. We establish that by recording photon correlations from optimally positioned detectors on top of coupled waveguides with detuned propagation constants, one can perform robust reconstruction of multiphoton density matrices describing the amplitude, phase, coherence and quantum entanglement. We report proof-of-principle experiments. Our method opens a pathway towards practical and fast inline state tomography for diverse applications in quantum photonics.

Lithium niobate is widely used in photonics applications because of its large second order nonlinearity and the possibility of integrating nonlinear parametric processes and fast electro-optical reconfigurability. Here we show how these properties can be used for continuous variable quantum optics experiments including the generation, manipulation and characterization and detection of squeezed light.

Accessing complete information about the emission from any quantum-optical systems requires tools capable of a frequency-resolved characterization of multi-photon transitions that would go beyond the standard g^{\left(2\right)} correlation measurements. In this work, we calculate and analyze in details correlations of light emitted from two such canonical nonlinear optical systems, one incorporating Kerr nonlinear medium, and another exhibiting optomechanical coupling between light and quantized motion of a generic mechanical oscillator. Our analysis shows a rich landscape of bunching and antibunching associated with multi-photon emission events, and reveals the distinctive temporal characteristics of such processes.

We experimentally demonstrated a quantum information processing advantage in a Bernoulli factory – a processor that transforms one probability distribution into another. We used photon-encoded operations to show the enhancement with two different techniques: one using quantum coherence and single-qubit measurements; and the other one using quantum coherence and entangling measurements of two qubits. It is theoretically known that it is computationally difficult to transform fair coin tosses to particular, relevant probability distributions using classical techniques. Our quantum methods achieve an advantage of several orders of magnitude in resource consumption compared to classical methods, and demonstrate an improved scaling.

The development of mid-infrared fibre sources of light is reaching new levels of power, efficiency and wavelength coverage. In this talk I will briefly review the major achievements that have resulted in the record performance and I will outline the challenges and opportunities ahead.

A holmium non-linear polarisation rotation (NLPR) mode-locked fibre laser was characterised and automated. The laser was automated using pulse train radio-frequency (RF) spectra measurements. Amplitude modulation across small bins over a broadband RF range was used as a metric to find a stable pulsed (continuously mode-locked) regime by changing the cavity’s polarisation state as necessary. Optimum laser operation produced sub-ps pulses with a central wavelength of 2.061 µm with 8.7 nm optical full-width-at-half-maximum (FWHM). Future work will include splicing dispersion compensating fibre into the cavity and obtaining an accurate pulse duration measurement using an autocorrelator.

The yellow spectral region has applications in medicine, ophthalmology, acne treatment, and ytterbium based optical clock, which is recommended as the secondary representation of System International (SI) second. Lasing in this spectral region can be achieved by using sum frequency and second harmonic generation, which are complex methods. Here, we have reported the first (to the best of our knowledge) GaN laser diode pumped dysprosium (Dy) doped ZBLAN fibre laser for yellow lasing using a simple setup. Due to the four-level system, the laser oscillation threshold is low and about 7.0 mW for 0.6 m of Dy-doped ZBLAN fibre. However, the maximum slope efficiency is only 2.3% with the available 2% output coupler. In our investigation, we have identified two possible factors, fibre background loss and pump excited state absorption, for such a low slope efficiency.

A single-frequency thulium-doped fibre distributed Bragg reflector has been developed for characterisation of high power thulium amplifiers for gravitational wave detection. A 3cm laser cavity was fabricated with custom high dopant concentration silica fibre. In-band pumping was provided by a 1550 nm fibre coupled diode and emission was observed at 1951 nm. Maximum output power of 67 mW was measured, limited by the available pump power. Single-longitudinal-mode operation was confirmed with a scanning Fabry-Perot cavity, indicating a linewidth of 100 kHz.

We describe the lasing behaviour of an all-fibre laser with saturable absorber with emphasis on observed hysteresis and bi-stable dynamics for certain parameter regimes. The fibre laser is a simple Fabry Perot cavity with Erbium and thulium doped sections that provide optical gain and saturable absorption respectively. We explore methodically laser behaviour for consecutive up and down scans of optical pump powers for up to 13 unique experimental configurations using different lengths of the absorber section (ranging from 0.21~m to 1.48~m). We report interesting bistable behaviour as well as hysteresis which exists for a narrow range of saturable absorber lengths(0.66~m to 0.78~m).

Entanglement is a key resource of disruptive quantum technologies and the quest of efficient sources a thriving area of research. Notably, multipartite entanglement is required in a number of quantum information, computation, and communications protocols. Optical networks are of great interest in this context and nonlinear χ(2) waveguide arrays can provide a compact source of multipartite entanglement by embracing nonlinearity and coupling. We report on our theoretical results in investigating multimode entanglement in nonlinear waveguide arrays which could be implemented using periodically poled Lithium Niobate (PPLN) waveguides.

Random numbers are integral for cryptography, data science and fundamental research. Quantum random number generators derived from the processes of quantum mechanics ensure fundamental randomness, and many demonstrations have been implemented measuring, radioactive decay, vacuum fluctuations, and single photons in superposition states. Advancements in on-chip photon coupling, state manipulation and detection are bridging the gap towards quantum optical circuits, but typically require the use of probabilistic photon sources or cooling to cryogenic temperatures. In this work, we use a hexagonal boron nitride single photon emitter , a true deterministic quantum light source operating at room temperature, coupled to a multiplexing photonic chip to generate random number sequences.

Quantum communication requires long-lived memories and robust communication qubits. Long-lived memories and high fidelity two qubit gates are demonstrated using atomic qubits. Frequency qubits are shown to be robust against noises present in long distance communications. In this project we are working towards using trapped 171Yb+ ions as memory qubits and frequency encoded photonic qubits as communication qubits to realise long distance quantum communication protocols.

Frequency combs, analogue to digital sampling, and free space optical communications are emerging applications that can benefit from advances in elegant, compact, and high-performance miniature mode-locked lasers. By virtue of their ‘chip-scale’, and multiplicity of adjacent waveguides, compact planar waveguide devices are suited to efficiently operate in the ~0.5 GHz to 10 GHz pulse regimes, and to have key advantages when employed as dual-frequency combs. The erbium ytterbium cerium co-doped ZBLAN chips we have developed have achieved transform limited mode-locked output near 1.55 µm, pulse lengths down to 180 fs, and operation up to 5 GHz. This paper will also cover our more recent work on demonstrating a dual-frequency comb based on simultaneously mode-locking adjacent waveguide lasers in a common-cavity setup and demonstrate its spectroscopic potential by rapidly (~ms) acquiring high resolution and broad (>2 THz) molecular spectra of molecules.

High-power single-longitudinal-mode (SLM) lasers are crucial for applications such as LIGO and sodium guide stars, but are challenging due to gain profile inhomogeneities and spatial hole burning. This work shows that a 38 W SLM 620 nm laser is firstly achieved using a standing-wave diamond Raman resonator with intracavity second harmonic generation (SHG). In addition to the benefits of the spatial hole burning-free gain medium, SHG provides a valuable additional mechanism for increasing gain competition and therefore enhancing SLM stability. Nascent secondary modes experience double the nonlinear loss in the SHG crystal due to the role of sum frequency generation with the primary mode.

We report on the latest results towards a compact ultra-high repetition rate Yb-doped fluorozirconate laser. We designed and constructed a passively mode-locked laser system based on our previously demonstrated high efficiency continuous-wave Yb-doped chip laser. Preliminary results based on a simple and robust extended cavity design show a laser which operates with a pulse width of 2.5 ps and a repetition rate of ~276 MHz at λ = 1018 nm. By controlling the dispersion and intracavity loss it should be possible to decrease the pulse width and increase the repetition rate to multi-GHz range.

We consider four-wave mixing in magnesium fluoride microresonators with diameters less than 1000 microns. Contributions from geometric dispersion permit phase matching at large frequency separations. By using a conventional C-band laser we observe pairs of sidebands are as far away as 1 and 3.8 microns. By tuning pump and using resonators with different sizes, all intermediate wavelengths can be accessed via discreet tuning. We also demonstrate regions of continuous tunability, mediated by a thermo-optic effect, observing continuous tuning over 10 GHz. Thus, we demonstrate a systematic method of generating broadly tunable light that operates over multiple octaves.

We propose solving the “non-conjugation” problem with an unstable ring resonator. By placing both the Nd: YAG slab and the deformable mirror in the collimated portion of the ring resonator, the required surface shape of the deformable mirror is exactly conjugate with the phase aberrations of the slab. We established a unidirectional unstable Nd: YAG slab ring laser, and integrated an adaptive optics system into the resonator. After compensation, the beam quality was improved from 14.9×DL to 3.5×DL at output power of 487W.

Supercontinua generated in microstructured optical fibre exhibit extreme spectral broadening. A theoretical gravity-like potential model requires NIR Raman self-frequency shifted solitons in the anomalous dispersion region to be phase matched with the short wavelength dispersive waves travelling in the normal dispersion region of the fibre. Observing effects in the fundamental EM mode of the host fibre is difficult so, specific high order EM modes were excited, generating a spectrally sparse supercontinuum providing unequivocal evidence of phase matching when studied using polarisation and spatio-spectral mapping.

We report a fibre laser incorporating an intracavity pulse-shaper that induces a large anomalous net cavity quartic dispersion in which the mode-locked pulses propagate as pure-quartic solitons. We characterize the laser output pulses using a set of spectral and temporal phase resolved measurements and resonant dispersive wave analysis, and find that the results are in excellent agreement with analytic predictions.

We enhanced the Kerr nonlinearity of a doped silica waveguide by integrating layered graphene oxide (GO). Owing to strong mode overlap between the integrated waveguides and GO films that have a high Kerr nonlinearity and low loss, the FWM efficiency of the hybrid integrated waveguides is significantly improved. The Kerr optical nonlinearity is enhanced experimentally by integrating layered graphene oxide (GO) film on waveguides. The conversion efficiency of four wave mixing (FWM) is enhanced by up to 9.5 dB in a 1.5-cm-long waveguide. We perform FWM measurements for different pump powers, wavelength detuning, GO coating lengths, and the number of GO layers. Our experimental results show good agreement with theory.

Self driving cars offer the potential to be a safer, more economical and more environmentally friendly transport option. High performance LiDARs are one of the primary enabling sensing technologies vital to autonomous vehicles to meet the demanding requirements for full autonomy. We discuss the role of automotive LiDAR in autonomous vehicles, and the performance requirements and optical technologies that high performing LiDARs need to achieve to fulfill that role.

Optical phased arrays (OPAs) are a solid-state device able to manipulate the distribution of optical power in the far-field without the use of mechanical beam steering systems. OPAs have potential applications in technologies such as free-space laser communications, adaptive optics, target acquisition and tracking, satellite interferometry, and light detection and ranging. Here we present a scalable OPA and digital control architecture capable of steering a laser beam at MHz frequencies, and having arbitrary control over the beam wavefront.

High performance beam steering techniques are essential for 3d imaging systems, and in particular automotive lidar. We present a high-speed, chip-scale, dynamically reconfigurable beam steering system suitable for use at telecom wavelengths. Our technique relies on sub-microsecond electro-optic switching between discrete outputs in a waveguide network. This beam steering technology, along with a coherent detection technique is used to demonstrate simultaneous ranging and doppler velocimetry of targets with a solid state lidar system in a laboratory environment.

We present a Light Detection And Ranging (LiDAR) perception sensor capable of automatically prioritising measured information based on velocity and range with strong immunity to interference (e.g., other LiDAR sensors, glare). By automatically prioritising measured information based on velocity and range, our aim for this sensor is to reduce the processing time required to execute safety-critical decisions in autonomous applications. It utilises commercially-available telecommunications-grade hardware, as well as the latest generation of system-on-chip (SoC) field-programmable gate-array (FPGA) technology to create a sensor that is entirely software-defined.

Time reversal of waves exploits the linearity of wave propagation. It consists in propagating a short pulse in a turbid medium, recording it, and playing it backwards to focus back to the source. Such time reversal control has been evidenced for low frequency waves such as acoustics, water waves and microwaves. Partial spatiotemporal control of optical waves has been demonstrated recently, nonetheless full optical time reversal remains elusive. Using a spatially and polarization resolved spectral pulse shaper, we demonstrate for the first time the ability to generate arbitrary spatiotemporal field after propagation through a multimode fiber.

The James Webb Space Telescope mission is designed to provide unprecedented performance at near- and mid-infrared wavelengths, and with a suite of sophisticated imagers and spectrometers it is poised to deliver revolutionary science. With a 6.5m diameter primary mirror it will be the largest and most ambitious astronomy mission launched. In this talk I will give a broad overview of the mission and its current status and scientific prospects. The expected performance and capabilities of the instruments will be presented along with the plans for early scientific observations.

We will present our current developments in Programmable photonic integrated circuits (PIC). These generic optical circuits, which consist of a network of tunable couplers and phase shifters, can be electrically controlled to perform different functions. In this, they form an optical equivalent to an FPGA. This new class of PICs requires different use of electro-optic drivers and monitors, advanced packaging, and additional layers of software, compared to today’s application-specific PICs. But they can be used for different applications, and their programmability can pave the way for rapid prototyping of new photonic circuits.

In this contribution, we demonstrate the deposition of low loss, CMOS-compatible SiN thin-films using reactive sputtering with and without plasma beam assistance for photonic integrated circuits. Plasma beam assistance during the deposition process enabled us to achieve a thin-film loss of below 0.1 dB/cm and a surface roughness Rq of <0.1 nm, while keeping the processing temperatures below 400 °C. Then we fabricated waveguides with the deposited SiN as waveguide core material and demonstrated a ring resonator with a quality factor (Q) of up to 1.62 x 105 at 1565 nm, which corresponds to waveguide losses of 2.2 dB/cm.

The detection of quantum errors is of particular importance to the development of reliable engineered quantum systems. Whereas previous error-detection schemes were mostly developed for Pi phase-flip associated with solid-state qubits, here we introduce a protocol for direct detection of arbitrary continuous phase errors in the transmission of multiphoton spatially entangled quantum states. We present a design and experimental evidence for its realization in an integrated photonic circuit using gradually coupled waveguides with specially detuned propagation constants. We anticipate that our approach will facilitate the development of error-robust photonic devices for the processing and communication of quantum information.

A CMOS compatible three-dimensional (3D) integrated photonics circuit for multilayer silicon photonics is reported. Slopes with angles between 10o and 15° were created in the oxide layer using single step wet etching to connect the two Si waveguide layers. Amorphous Si (a-Si) deposited using hot wire chemical vapor deposition (HWCVD) at a temperature of 230°C was used to fabricate the device. Losses of 0.5 dB/slope were measured in the slope waveguides at 1310 nm wavelength. As a demonstration, we propose a 4x4 network switch using a-Si based vertical directional coupler.

Biomolecular analysis of living organisms at high speed and throughput represents a grand challenge in the life sciences, which can only be met by a photonic technology. We pioneered multispectral imaging of native fluorescence of cells and tissues which allows precise quantification of biomolecular composition of cells and tissues. Using a big data approach and building on high processing speeds of modern computers we are now able to monitor biomolecules such as NADH, flavins, retinoids, cytochrome C and many others, and make precise colour and morphology based distinctions between cell groups. This provides highly sensitive insights into metabolism and its dysregulation, particularly in cancer, neurodegeneration, immunity and a range of disease conditions. I will describe how this new “window to the body” will transform medical diagnostics and drug discovery.

The rapid measurement of gas concentrations is beneficial to a broad range of applications, including pollution monitoring, high-precision spectroscopy, and medical breath analysis. Optical frequency combs (OFCs) are a near-ideal optical interrogation source for molecular spectroscopy, combining broadband light with high frequency-precision and dense spectral sampling, characteristics which also allow short measurement times. A spectrometer based on a virtually imaged phased array (VIPA) is used to unravel the comb into a high-resolution transmission spectrum, with the returned spectra rapidly fitted with a detailed spectral model for concentration extraction of CO2. We demonstrate high accuracy and precision concentration measurements for the two most abundant CO2 isotopologues, and demonstrate the high linearity of the system. Additionally, we demonstrate the use of a multi-pass Herriott cell to continuously monitor CO2 production during the respiration of baker’s yeast.

Quantum optical information systems offer the potential for secure communication and fast quantum computation. To fully characterize a quantum optical system one has to use quantum tomography. The integration of quantum optics onto photonic chips provides advantages such as miniaturization and stability, significantly improving quantum tomography using both re-configurable, and more recently, simpler static designs. These on-chip designs have, so far, only used probabilistic single photon sources. Here we are working towards quantum tomography using a true deterministic source - an InGaAs quantum dot.

The concept of using multiple-pass technique to improve the axial resolution of a reflection mode confocal system is presented. The propose technique allows further diversion on the given out-of-focus rays from entering the pinhole, imposing a more stringent limit for rays around the in-focus region to be detected as confocal signal. The feasibility of the propose technique was experimentally examined. The comparison of the full width at half maximum (FWHM) of the normalized intensity profiles shows that the axial scanning resolution achieved by the proposed technique is twofold of that of the conventional technique.

Power scaling of narrow linewidth laser source through fiber amplifiers is usually limited by nonlinear processes, specifically due to the onset of stimulated Brillouin scattering (SBS). The stimulated Brillouin scattering process results in a backward propagating Brillouin Stokes wave at a down shifted frequency due to scattering from acoustic phonons in optical fibers. The backscattered Stokes radiation exhibits intensity variations with respect to time due to the spatially distributed and temporally fluctuating Langevin noise source. We investigate the nonlinear optimization of periodic phase modulation to achieve RF signals that represents the best tradeoff between SBS threshold enhancement and optical linewidth. We will present experimental and simulation results leading to the demonstration of power scaling in a narrow linewidth fiber amplifier.

testtes

We present two new designs of optoacoustic waveguides supporting nonlinear Brillouin scattering (SBS). The first design comprises a rectangular core supporting a low-loss optical mode, suspended in air by a series of transverse ribs. The ribs are engineered to exhibit a complete acoustic stopband and suppress the transverse leakage of acoustic waves. The second design we discuss here is a realization of an Anti-Resonant Reflecting Acoustic Waveguide, which are analogues of optical ARROWs. These waveguides, capable of co-localization and guiding of both the optical and GHz acoustic waves in simple, translationally invariant waveguides, are shown to support backwards SBS.

An integrated waveguide polarizer and polarization-selective micro-ring resonators (MRRs) incorporated with graphene oxide (GO) films were experimentally demonstrated. A high waveguide polarization dependent loss of ~53.8 dB is achieved for the waveguide coated with 2-mm-long patterned GO films. It is found that intrinsic film material loss anisotropy dominates the performance for less than 20 layers whereas polarization dependent mode overlap dominates for thicker layers. For the MRRs, the GO coating length is reduced to 50 µm, yielding a ~ 8.3-dB polarization extinction ratio between TE and TM resonances.

We have investigated the effect of the frequency shift associated with an acousto optic (AO) interaction on the spectral quality of acousto optically tuned external cavity semiconductor lasers. A ring cavity was built and the wavelength controlled by a frequency compensating acousto optic tunable filter pair, which allowed user control over the frequency shift of the interacting light. Laser spectra were recorded for a range of frequency shifts, and a 30 kHz driving frequency gave the optimal spectral response where the output spectral shape did not vary as a function of operating wavelength and resulted in <0.1 nm linewidths.

The development of the first Yb3+ doped microchip and waveguide laser in germanate glass (GPGN) is reported with a composition of 54GeO2-31PbO-4Ga2O3-9Na2CO3-1.5Yb2O3 (Yb3+: GPGN). Up to 51mW at 650mW of input power is obtained from a L=4.5mm long cavity microchip laser operating at 1052nm with slope efficiency of ~30% and laser threshold of ~230mW. Single track (type 1) waveguides are inscribed 150µm beneath the surface of the sample in the femtosecond laser cumulative heating regime. Pulse energies range from15nJ to 75nJ producing guiding structures ranging from d= 12µm to 60µm. Waveguide laser operation is achieved for a 24µm diameter waveguide with up to ~20mW output power generated at 1.07µm for 650mW of 976 nm pump power.

We demonstrated a compact design for a 1064 nm Q-switched laser based on a liquid crystal transducer, in which the in-coupling mirror is integrated, and the Grin lens could also be butt coupled with the waveguide chip. The primary experimental results have demonstrated that the Q-switched laser pulses with the pulse width of 45 ns and average output power of 4.5 mW can be achieved with the pump power of 350 mW, when the electrical signal with the repetition rate of 5 kHz, the peak-to-peak voltage of 30 V and the duration of 4 microseconds is applied to the device.

Coherent excitation and stimulated emission from optical transitions has been proposed as a mechanism to generate strong coherent forces in atomic systems and as the basis for fast quantum gates in trapped ions. We have demonstrated driving coherent oscillations between the 2S1/2 and 2P1/2 states in trapped 171Yb+ with 2.5 ps pulses straddling the resonance at 369.5nm. At higher powers nearly full extinction was observed, demonstrating coherence, however residual detuning issues have precluded full coherent population transfer.

We demonstrate the first stable mode-locking from an Er3+ doped fluoride fibre laser cavity using various novel two-dimensional saturable absorber materials such as PtSe2 and MXene operating near 2.8 µm wavelength to the best of our knowledge. The linear cavity includes a high reflective chirped fibre Bragg grating to provide wavelength stability. The observed mode-locked pulse train has a 30 MHz repetition rate and an average power of 223 mW. Our results demonstrate the feasibility of using the novel two-dimensional nanomaterials such as PtSe2 and MXene into the fibre laser cavity for the application in mid-infrared wavelength regime.

Improving the sensitivity of gravitational wave detectors will require accurate mode matching of beams in the interferometer. We propose exploiting the optical absorption by residual OH in the interferometer mirrors to provide active correction of this mode mismatch. To demonstrate this technique, we developed a wavelength stabilised, watt-level, Er:ZBLAN fibre laser with emission centered at 2.78um. This laser beam was used to heat a high purity silica mirror. The resulting wavefront change, which was measured using a Hartmann wavefront sensor, was highly spherical with low levels of higher order aberration.

We report mid-infrared supercontinuum generation in a silicon germanium-on-silicon waveguide. We show that, by adding a chalcogenide cladding, it is possible to trim a posteriori the waveguide’s dispersion profile which, in turn, governs the properties of the generated supercontinuum. In particular, we experimentally show that a shift from anomalous to normal dispersion takes place when a 1.26 µm thick cladding layer of Ge11.5As24Se64.5 is added. Finally, we show that the group velocity dispersion of the waveguide can be precisely controlled by changing the thickness of the cladding layer.

Compared to oxide based glasses, vitreous materials composed of chalcogen elements (S, Se, Te) show large transparency windows in the mid-infrared. Indeed, chalcogenide fibers can be transparent from the visible up to 12-15 µm, depending on their compositions. Various chalcogenide microstrutured optical fibers (MOF) operating in the mid-IR range have been elaborated in order to associate the high nonlinear properties of these glasses and the original MOF properties.. Indeed, chalcogenide MOFs might lead to new devices with unique optical properties in the Mid-IR domain like multimode or endlessly single mode transmission of light, small or large mode area fibers, non-linear properties for wavelength conversion or generation of supercontinuum sources. In this work, a supercontinuum from 2 to 10 µm, with an average power of 15 mW, has been obtained in a chalcogenide MOF by pumping with a supercontinuum generated in a fluoride fiber.

A long-term research program has been in place at the Wyant College of Optical Sciences to apply interferometry to ophthalmic applications. The first developed system is a transmission Mach-Zehnder interferometer that measures the transmitted wavefront of a contact lens while it is submersed in saline in order to determine the refractive power distribution of the lens. A second system makes use of a low-coherence interferometer to measure the index of refraction of contact lens materials. This system measures very thin samples that must remain hydrated in saline during the measurement. An additional interferometer examines the dynamics of the tear film on the surface of the cornea (in vivo) and also functions as an interferometric corneal topographer. This system is an instantaneous phase shifting Twyman-Green interferometer. The evolution and changes to the fluid surface are measured at video rates with sub-wavelength precision.

We report the characterization of arrays of micropillars fabricated in an n-type 4H-SiC using photolithography to enhance the emission of bandgap color centers in silicon carbide emitting in the spectral region from 850 nm to 1400 nm. The emission is identified by the mono-vacancy of Si (VSi), silicon and carbon divacancy (VCVSi), and the nitrogen-vacancy (NCVSi) using low-temperature micro-photoluminescence. These emitters are created in large ensemble by using ions implantation and annealing at a different temperature to extend the emission in the O-band region. The optical fluorescence enhancement experimental results are obtained using custom made IR confocal microscope to measure integrated PL of up to a factor of 20 compared to bulk material. This enhancement is supported by finite-element simulations considering the non-unity quantum efficiency of the emitters and their broad spectral emission at room temperature. Our study provides the pathway for quantum sensing device design

The precision of modern spectroscopy affords optical tests of fundamental physics in helium through, for instance, nuclear charge radii determinations. Helium therefore provides a testbed as appealing as Hydrogen for spectroscopic tests of QED. Among outstanding discrepancies between predicted and observed Helium transition lines are the 7.5-sigma difference in the n=3 singlet-triplet splitting and the 93-sigma difference between measurements by Martin and recent predictions by Drake of the n=2 to n=5 interval. We contribute to both of these by measuring five transitions from the 2-3P2 state, improving on Martin's measurements with an order of magnitude greater precision, and making the first observation of the spin-forbidden 2-3P2 to 5-1D2 transition in Helium. Our measurements constrain the 5-3D and 5-1D ionization energies of Helium-4 to 150 parts per billion, and the 5-3S to 28 parts per billion.

There are a myriad of commercial material processing applications requiring a low-cost laser affording both excellent beam quality and output power exceeding 1.5kW. Fibre lasers offer a potential solution to both objectives but further simplification of system architecture is a prerequisite for further cost savings. More specifically, it would be advantageous to avoid the use of expensive triple clad fibres and the deployment of MOPA architectures, which are potentially vulnerable to back-reflection from the work-piece. Similarly, one needs to avoid the inevitable duplication of build-time and components associated with combining output from multiple lower-power cavities. Unfortunately, the availability of a fibre that can routinely achieve 2kW and above has to date proven elusive. In this presentation, we describe the results of a study into fibre designs that afford mass-manufacture of simple, cost-effective multi-kW oscillators. We consider a wide variety of customer system architectures, deployment conditions and choice of pump wavelength to arrive at fibre designs that simultaneously mitigate the onset of Stimulated Raman Scattering (SRS) and Thermal Mode Instability (TMI).

We demonstrate a theoretical study of nanohole arrays perforated on a metallic layer (Al) arranged in a square lattice. The impact of the hole periodicity, thicknesses of Si3N4 and metallic layer are studied. We report the implementation of a surface plasmon resonance for the application of highly specific CMOS compatible plasmonic color image filters. A perforated aluminum layer on the hybrid substrate exhibits high transmission and high selectivity for additive colors by using a square lattice. The proposed design can be realized by a simple fabrication method and has minimum color cross talk.

We have compared the performances of Bismuth/Erbium and Ytterbium/Erbium co-doped fibers as pumped to 808nm to one as pumped at 830nm. The pumping excitation conditions and spectral characteristics in BEDF and EYDF are explored to maximize the lasing efficiency. The fabricated codoped fibers could be useful as an ultra-wide gain medium with proper pump wavelength choice, covering 1000-1700nm telecommunication bands for the next-generation WDM passive optical networks employing single broadband amplifier or tunable fiber laser.

Distributed pressure profile measurements from the lifting surfaces of aerospace and maritime platforms provide valuable information to validate model predictions during design certification processes. These measurements are typically made on scale models of the structure in wind or water tunnels and require the sensors to be integrated into the model with minimal intrusion on the surface. The minuteness and capacity for multiplexing of optical fibre-based sensors offer potential for successful application in this area. This paper reports on an experimental assessment of three distributed fibre optic pressure sensor designs intended for integration with the lifting surfaces of composite marine propellers.

The Shannon capacity limit will soon be reached. One way to break the limit is to use Nonlinear Fourier transform (NFT) to design communication channels. When designing such systems, one may need to maximise the usage of NFT bandwidth by packing eigenvalues (nonlinear frequencies) as close as possible. The consequences of doing so have not been previously studied. We attempt to fill this gap though the study of soliton pulses with two close eigenvalues. The results show strong correlations in eigenvalues, NFT spectral amplitudes and phases. A model is then built to explain the potential source of these correlations.

High levels of mode matching are required for optimal performance in interferometric gravitational wave detectors that use squeezed light injection. We propose a technique for measuring the magnitude and direction of mode mismatch by inducing a radio frequency waist size and position modulation and demodulating the reflected field using a single element photodiode.

To overcome the crosstalk happening between two degenerately fundamental modes of a fiber in Terahertz (THz) regime, a novel photonic crystal fiber (PCF) that yields a wide range of single-polarization-single-mode (SPSM) propagation with large loss differences (LDs) is designed. The method used to realize this SPSM PCF is to deposit an epsilon-near-zero (ENZ) material in four selected air holes in the cladding, which ends up with four ENZ rings. These ENZ rings introduce significant LDs between the wanted (X-polarized) and unwanted (Y-polarized and high order) modes. Extensive simulation results demonstrate that the LDs between the wanted and unwanted modes vary with the thickness of ENZ rings. With a very short length (4 cm) of the proposed PCF, pure SPSM propagation, i.e., the unwanted modes are 20 dB lower than the wanted mode, can be achieved from 1 to 1.2 THz.

The device characteristics of GaSb-based mid-infrared (MIR) photonic-crystal (PC) surface-emitting lasers (SELs) were investigated with respect to depths of etched PC holes. Measurement of below-threshold emission spectra identifies the bandgap as well as band-edge modes. The bandgap separation, which is a function of feedback coupling, increases with increasing depth. From within, the Bragg frequencies and their detuning from lasing frequencies can be determined. Moreover, with increasing depth, the threshold pumping density decreases exponentially to a saturation level, which is assigned to minimum device modal gain of certain value. The relative threshold gain is then plotted as a function of normalized frequency detuning. The gain-detuning relationship of PCSELs is similar to that of one-dimensional (1D) distributed feedback (DFB) lasers.

A novel polyvinylidene fluoride (PVDF) coated fibre-optic Fabry–Perot interferometric (FFPI) sensor formed by the immersion precipitation process on a cleaved single mode telecommunications optical fibre end face is proposed for temperature measurement and experimentally validated. Sensor operation was demonstrated by shifts of the FFPI reflection spectra and its performance was analysed through measurement of optical path difference with temperature variation. The sensor demonstrated an exponential response over the temperature range 21 to 160 °C with a sensitivity spanning between 1.6 and 7.5 nm/°C and a temperature resolution of 0.01 °C.

In this paper, we study the Nonlinear Fourier Transform of a signal formed by adding two time-separated pulses. By using the layer peeling property, we show that the eigenvalues of the signal are well approximated by the union of those for the two component pulses separately. The accuracy level of the approximation increases as the component pulses are further separated in time. Scattering coefficients and spectral amplitudes of the signal are also derived, which explain the correlation in eigenvalues, scattering coefficients and spectral amplitudes between the signal and the component pulses.

In this study, two fiber Bragg grating sensors are multiplexed using time division multiplexing. The fiber Bragg gratings are setup in a dual bus configuration and the sensor signals are detected using a transmit-reflect detection system. The results demonstrate that both the transmitted and reflected signals from both fiber Bragg gratings can be resolved when the sensors are separated by a sufficient distance.

Motivated by available methods in quantum mechanics, we have developed a novel method to find the nonlinear Fourier transform (NFT) of optical signals. Using this approach, we are able to analytically solve the matrix eigenfunction-eigenvalue equation that describes NFT and reduce it to an ordinary first order scalar differential equation. This simplifies the processes of finding the NFT of any optical signal and can potentially lead to more efficient and accurate numerical methods to find NFT.

Conducting polymers are widely researched in terms of both their electrical and optical properties. In this study microscale volume poly(3,4-ethylenedioxytiophene)-tosylate (PEDOT:Tos) layers are fabricated at the tip of the single mode optical fibre. This allows for optical interrogation (primarily at 1550 nm) of the properties and behaviour of PEDOT:Tos. The optical response (back-reflection and transmission) of the PEDOT:Tos and the effect of different oxidant solution on the laser-induced damage threshold measured. The size and understanding of structural change in PEDOT:Tos revealed by these experiments will lead to improving the lifetime and better perception of PEDOT for future sensing applications.

Hybrid integration of different materials will allow for different functionalities such as passive, amplifying, nonlinear, electro-optic, detection etc to build “system on a chip” devices. The vertically stacked layer design commonly proposed significantly increases the difficulty of the lithography process for the bottom-most layer due to the overlying topology. A methodology for significantly improving the fabrication tolerance of planar directional couplers is therefore presented. A parametric design study reveals that significant dimensional sensitivity improvements exist for certain center-to-center spacings for both power and wavelength splitters. Wavelength splitters can also exploit raising the ratio of coupling coefficients between the desired wavelengths.

We study photonic circuits consisting of cold-atom ensembles coupled to light modes of optical nanofibers and long lengths of connecting or feedback fibres, such that the propagation time of light along these fibres is comparable to the timescale of the atomic dynamics. This provides a non-Markovian setting for quantum dynamics and feedback. The fibre-based platform enables implementation of a simple configuration for time-delayed quantum feedback where light emitted from the atoms propagates along a length of fibre and is reflected back towards the atoms by a Fibre Bragg Grating (FBG) mirror. We will present the initial results of our experiments.

2D materials, led by graphene, have been widely explored in the last decade as saturable absorber (SA) materials. Most of this work has focussed on fibre compatible designs for use in fibre lasers (e.g. fibre connector sandwich, D-shaped fibre). Realising chip based mode locked lasers is an important challenge, and little work has been carried out on planar waveguide SAs, Here, simulation results for the absorption performance of two types of graphene based TeO2 waveguide SA designs with suitably high absorption and low saturation threshold are presented.

We propose a method to improve the performance of unidimensional continuous-variable quantum key distribution with imperfect detector by adding a phase sensitive amplifier, where the imperfect detector affects the performance of the protocol and are difficult to adjust in an experiment. It is found that the optimal performance can approach the scenario with a perfect detector.

The ability to perform spatially resolved measurement of extreme temperatures, the order of 1000°C and above, would yield enormous benefit to many heavy industrial processes. While optical fibers can provide spatial information along their length through distributed and multi-point sensing techniques, operation at such temperatures is an area of ongoing research and development. A challenge is that conventional optical fibers, fabricated with a chemically doped core, suffer dopant diffusion at these high temperatures, ultimately limiting their operating lifespan. We can overcome this limitation by using specialty pure silica glass fibers, such as microstructured optical fibers. In this work we demonstrate the ability to use such fibers in a significantly multiplexed configuration with twenty fiber Bragg grating sensing elements written via femtosecond laser ablation.

There is growing demand for biodegradable polymer fibres in tissue engineering and nerve regeneration. We demonstrate a scalable and inexpensive fabrication technique to produce polycaproactone (PCL) fibres using fibre-drawing technique. Here we report on the first successful drawing of hollow-core and solid-core PCL fibres of different cross sections. The demonstrated capacity to tailor the surface morphology of PCL fibres, together with their biodegradability and tissue compatibility, makes them a unique material base for tissue engineering and nerve regeneration applications.

We demonstrate a high-Q RF transversal filter based on a 49GHz-FSR integrated microcomb source that provides 80 taps across the C-band. By employing an on-chip micro-ring resonator, we generate a broadband Kerr comb with a large number of comb lines and use it as a high-quality multi-wavelength source. A Q factor of 73.7, an out-of-band rejection of 48.9 dB, and a wide tunable range are demonstrated. The experimental results verify the feasibility of our approach as a solution towards implementing highly reconfigurable MPFs with a large tap number and reduced system complexity.

When the surface of the test object is rotated substantially, the initial value estimation can have a major influence on the execution speed of DIC algorithm. This paper deals from two aspects to improve the efficiency of the initial value estimation algorithm for large-rotation objects. Firstly, we decomposed images into multiresolution layers to create wavelet pyramids. The multiresolution processing provides an efficient method for registering large image because the full-size does not require matching. Secondly, we further proposed the local ring pattern, which is invariant to object rotation, to convert the 2D template into a 1D grey value sequence for calculating the correlation coefficients.

We experimentally demonstrate nanostructured silicon photodetectors which consist of subwavelength arrays of vertically-oriented waveguides etched into a P-I-N vertically doped Si substrate. Our device combines both spectral-filtering and photocurrent-generation in one all-Si structure. We show that absorption and responsivity spectra of these nanophotonic devices can be tuned by appropriate geometric design.

The Alpine Fault of New Zealand serves as the primary boundary between the collision of the Australian and Pacific tectonic plates. In recent years the fault has attracted widespread attention as studies have shown that it produces large scale seismic events every ≈ 330 years, and that such an event is due[1][2]. In this research, we investigate distributed fibre optic sensors (DFOS) for continuous monitoring of the temperature profile in the 893 m DFDP-2B borehole located in Whatoroa. DFOS are able provide insight into temperature and strain variations along a fibre length with a high level of accuracy. Consequently, we construct a Raman Optical Time Domain Reflectometer operating at 1064 nm to interrogate the existing multimode fibre loop installed in the borehole. The continuous interrogation and resultant temperature profiles will provide new insight into phenomena occurring around the active fault.

The mid-infrared spectral region is of tremendous importance in scientific and industrial applications. A planar integrated low-cost sensing device is yet to be achieved. Whilst instrumentation exists, a key missing element is a low cost broadband waveguide detector. Here, a parametric study is presented on light absorption across a broad spectral range in graphene coated waveguides, which shows much higher absorption can be achieved at short wavelengths with this dropping off by one order of magnitude by 10 µm. Based on simulation results, a waveguide detector design covering 1-10 µm with absorption >10 dB at all wavelengths is presented.

We demonstrate a robust, stable and compact spectral filter for use in quantum optics experiments by implementing Fabry-Pérot resonators within optical fibre using pairs of fibre Bragg gratings. With only temperature stabilisation, these devices show less than 20 MHz frequency drift over 12 hours with a maximum suppression of roughly 35 dB and overall transmission of 75%. These characteristics make fibre Bragg grating Fabry-Pérot resonators ideal for quantum optics experiments where single photon-level signals must be efficiently filtered from large optical fields.

We have shown that it is possible to injection lock a pulsed Vertical Cavity Surface Emitting Laser (VCSEL). This is a cheap source of nanosecond pulsed light with a background noise of approximately ten percent. An inexpensive source of narrow-band pulsed light such as this could find many uses in quantum optics, such as the development of high-bandwidth quantum memory.

We report on the development of a single frequency laser at a 2.099 µm, it featured a lasing threshold of 54 mW and slope efficiency of 3.9% with respect to absorbed pump power. This laser used a holmium-doped distributed Bragg reflector (DBR) structure pumped at 1.15 µm. Two distinct laser architectures (co-propagating and counter-propagating) were explored. A narrow linewidth output was achieved with a single longitudinal mode. Future work will see further optimization of the laser design including modifications to the cavity length and output coupler reflectivity. Applications for this source include precision measurement, coherent laser radar and beam combination.

The influence of disturbance frequency and sampling rate on the accuracy of calculation results in line-based fiber optic sensor is analyzed, and two new methods is proposed. Firstly, we use band-pass filtering to eliminate the effects of low-frequency noise. When any position is disturbed, null-frequency is used to obtain the optimal filtering range in real time. Secondly, the sampling rate of 0.5 MHz is raised to 2.5 MHz by using spline interpolation. Experiments show that the positioning accuracy of this method can be improved from 200 m to 40 m with the total length of sensing fiber is 40 km.

Coupling light between optical components with different waveguide geometries on photonic integrated circuits have become an imperative function for many applications. Herein, we propose an algorithm for the design of low-reflection adiabatic optical components using a constant coupling approach. Low reflectivity is important for optical components that are in close proximity to semiconductor optical amplifiers, where a reflectivity of less than -50 dB is required. We apply the algorithm to a polarization mode converter on the silicon-on-insulator platform, where we reduce the back reflection from -41 dB to -58 dB. We also show the tradeoff between the reduction in the reflected power and the resulting device length.

This work reports the photoluminescence (PL) properties of Er doped AS2S3 films (at 0.1 mol% concentration) fabricated by RF co-sputtering. As sputtered films are shown to exhibit PL degradation only on exposure to the combination of green light and water vapour due to photo-incorporation of OH groups through film nanostructural pores. Rapid Thermal Annealing is investigated as a possible remedy to this issue.

In this research, we demonstrate an optical system design of microscope type spectral reflectometry which is based on finite microscope system with reflective objective. The advantage of finite microscope system is less optical components, which leads to less UV and NIR attenuation for the purpose of thin film (~5 nm) and thick film (~100 μm) measurement. Adjustable illumination angle design is also included. The illumination light incident on the sample are designed as parallel as possible for increasing the reflective light rays from bottom of RDL.Our non-destructive solution can measure thin film as thin as 5 nm and the depth of high density RDL with line width/ space = 1 μm/ 1μm. Metrology results from RDL structure and SiO2/Si standard reference material are presented.

We propose the feasible design of a device that can offer a unique method for controlling the terahertz spectrum allocation exploiting existing photonics-based technologies. We successfully designed a multiplexer and demultiplexer using arrayed waveguide grating, where the device can multiplex and demultiplex four frequency channels (8.64 GHz bandwidth) in the same operating range defined by the IEEE 802.15.3d standard with at least 10 dB separation. This study reveals that proposed solution play a major role in maturing the next generation wireless communication (beyond 100 GHz) networks.

We introduce a new approach to infrared microspectroscopy – Optical-Photothermal Infrared (O-PTIR) Spectroscopy. We describe and illustrate how the novel use of an optical probe (532nm laser) enables significant enhancements in IR micro-spectroscopy, with ~20x improvement in spatial resolution compared to traditional IR microscopes (FTIR or direct QCL) and simultaneously acts as Raman excitation source, thus delivering IR and Raman microspectroscopy from the same spot at the same time with the same spatial resolution. We show 400nm IR spatial resolution on a polymer interface, sub-cellular IR imaging of live cells and sub-micron microplastics analysis with IR+Raman.

Transparent crystals of yellow-orange colour of 2-methoxy- 4(phenyliminomethyl)phenol also known as vanillylideneaniline (VAN) have been grown by slow evaporation solution growth method. Crystals of dimensions 5 X 5 X 3 mm¬3 were harvested after five days of crystallization process. The material was found to be crystallized in orthorhombic crystal system with non-centrosymmetric space group C2221. The index of refraction and absorption coefficient spectra of VAN were determined in the 0.25–2 THz frequency range at room temperature by THz time domain spectroscopy. Our measurements show that the material is not very absorptive to THz. The material is transparent enough to THz radiation and it may be worth to try the material for THz generation employing suitable phase matching techniques. The refractive index of VAN crystal is found almost stable around 2.4 from 0.25 to 1.5 THz.

Through this experiment, it can be seen that the analysis method of optical fiber transmission quality based on FPGA can monitor the transmission rate and bit error rate of the link on-line. Based on this hardware, it realized 10.313Gbps bi-directional data transmission with optical fiber and the outcome is fine.

We report a measurement for the 413 nm tune-out wavelength for metastable helium, at which there is no interaction between the atoms and the light. We use a new atom-laser based method to measure, to ten parts per million, the shift in oscillation frequency of a magnetically trapped Bose-Einstein Condensate with respect to the frequency of an optical probe. Our measurement of the shift zero crossing, at the tune-out wavelength, is accurate to (30stat)(150sys)MHz. This constitutes the most precise measurement of transition rate information ever made in Helium and probes QED effects in Helium[1].

The robustness of spontaneous symmetry breaking against controlled asymmetries is experimentally investigated in a fibre Kerr resonator. We remarkably find that different asymmetries can balance each other, resulting in the restoration of symmetry breaking phenomena.

The highly efficient modulation of the luminescence from upconversion nanoparticles combined with graphene oxide in a thin film was achieved at a millisecond timescale through the photochemical reduction of graphene oxide under UV irradiation. The increased absorption coefficient of the thin film accompanying reduction allowed ~90% quenching of the luminescence from the upconversion nanoparticles under near‐infrared excitation. Further, the instantaneous reduction in the intensity upon UV irradiation offers decreased modulation time of upconversion luminescence down to milliseconds at microwatt‐level power, providing a superior pathway for tuning upconversion luminescence with high contrast, fast reaction speed and low power consumption.

A broadband microwave mixer is demonstrated based on an integrated optical micro-comb source, with an operation bandwidth up to over 60 GHz, a conversion efficiency of −6.8 dB and a spurious suppression ratio of over 43.5 dB, and experimentally verify the RF performance up to 40 GHz. This approach to realizing microwave mixers offers reduced complexity, size, and potential cost for a wide range of applications to microwave systems.