Photonic integration based on silicon, silica, or indium phosphide technologies has reached a level of maturity where it has now become an integral part of telecom and datacom networks. However, although impressive levels of integration and bandwidth have been achieved, the performance of these technologies is relatively low, compared to fiber-optics and discrete bulk optics counterparts. This limits their application in more demanding fields like microwave photonics, e.g., for 4G/5G wireless communications, more advanced complex modulation formats for telecommunications, and highly energy-efficient interconnects. The invention of the ultra-low loss waveguide (ULLW) platform, by me and my co-workers at UC Santa Barbara, heralds a new range of applications for photonic integrated circuits. Fiber-like loss performance, with waveguide propagation losses < 0.1 dB/m, has been realized in waveguides with silicon nitride cores. This performance level represents an order of magnitude lower loss than silica-based waveguides, and 2 – 3 orders of magnitude lower than the silicon-on-insulator and indium phosphide PIC platforms. A combination of the silicon, ULLW, and/or indium phosphide platforms can be made using hybrid or heterogeneous integration techniques. Using “the best of both worlds” approach, improved performance can be achieved. I will discuss the opportunities that these technologies offer for various high-performance applications, such as low-noise lasers and oscillators, high-resolution radars and gyroscopes, and high-bandwidth photonic analog-to-digital converters.

With an ever-growing transmission data rate, electronic components reach a limit silicon photonics may overcome. This technology provides integrated circuits in which light is generated within hybrid III-V/Si lasers and modulated to transmit the desired information through silicon waveguides to input/output active/passive components such as wavelength (de-)multiplexers, fiber couplers and photodetectors. Nevertheless, high aggregate bandwidth through wavelength division multiplexing demands for spectrally narrowband lasers with high side-mode suppression ratio (SMSR). Distributed feedback (DFB) lasers offer such a great selectivity. We report hybrid III-V on Silicon DFB lasers emitting at 1550nm and 1310nm. The III-V material is wafer-bonded to patterned silicon-on-insulator (SOI) wafers. The laser cavity is obtained by etching a grating in the silicon, while silicon adiabatic tapers are used to couple light from/to III-V waveguides to/from the passive silicon circuitry, in order to maximize the laser available gain and output power. Gratings are either etched on the top of the silicon waveguide or on its sides, thus relaxing the taper dimension constraint. At 1550nm, the investigated device operates under continuous wave regime with a room temperature threshold current of 70mA, an SMSR as high as 45dB and an optical power in the waveguide higher than 40mW. At 1310nm, a threshold current of 35mA, an SMSR of 45dB and an optical power coupled into a single-mode fiber higher than 1.5mW are demonstrated.

In this communication, we report about the design, fabrication, and testing of echelle grating (de-)multiplexers for the 100GBASE-LR4 norm and other passive architectures such as vertical fiber-couplers and slow-wave waveguides in the O-band (1.31-μm) for Silicon-based photonic integrated circuits (Si-PICs). In detail, two-point stigmatic 20^th-order echelle gratings (TPSGs) on the 300-nm-thick SOI platform designed for 4x800-GHz-spaced wavelength division multiplexing featuring extremely low crosstalk (< -30 dB), precise channel spacing and optimized average insertion losses (~ 3 dB) are presented. Distributed Bragg reflectors (DBRs) are used to improve the grating facets reflectivity, while multi-mode interferometers (MMIs) are used in optimized perfectly-chirped echelle gratings (PCGs) for pass-band flattening. Moreover, 200-mm CMOS pilot lines processing tools including VISTEC variable-shape e-beam lithography are employed for the fabrication. In addition, wafer-level statistics of the multiplexers clearly shows the echelle grating to be inherently fabrication-insensitive to processing drifts, resulting in a minimized dispersion of the multiplexer performances over the wafer. In particular, the echelle grating spectral response remains stable over the wafer in terms of crosstalk, channel spacing and bandwidth, with the wavelength dispersion of the filter comb being limited to just 0.8 nm, thus highlighting the intrinsic robustness of design, fab pathways as well as the reliability of modeling tools. As well as that, apodized one-dimensional vertical fiber couplers, optimized multi-mode interferometers (MMIs) and extremely low-losses slow-light waveguides are demonstrated and discussed. The adiabatic apodization of such 1-D gratings is capable to provide band-edge group indices ng as high as 30 with propagation losses equivalent to the indexlike propagation regime.

Glass substrates have been used for decades to create biosensors due to their biocompatibility, low thermal conductivity, and limited fluorescence. Among the different types of sensors, those based on surface plasmon resonance (SPR) allow exploitation of the sensing lightwave at the vicinity of the sensor surface where small entities such as DNA or proteins are located. In this paper, ion-exchanged waveguides and SPR are combined to create a multianalyte optical sensor integrated onto glass. First the principle of operation is introduced, then the theoretical analysis and design of the sensing element. Simulations have been carried out using the Aperiodic Fourier Modal Method (AFMM) and a custom software that handles ion-exchange index-profiles. Fabrication and characterization processes are also presented. Finally the first experimental spectra are displayed and discussed. The sensor presents a bulk sensibility of 5000nm/RIU.

An analytical model to the modal characteristics of Metal-Insulator-Metal (MIM) plasmonic waveguide is proposed. An expression to the propagation constant and losses as function in the refractive index, the waveguide width, and the wavelength is obtained and verified using finite difference based mode-solver. These expressions are used to develop a theoretical model to the behavior of a plasmonic nano-filter based MIM configuration. The proposed model shows a good agreement with FDTD simulations. Using this model, the sensitivity of the filter to different design parameters is investigated and analyzed analytically. Therefore, the optimum values of different design parameters can be obtained analytically. By using this theoretical model, a sharp resonance filter with narrow bandwidth, compact size, low loss, and good sensing characteristics can be demonstrated. The proposed filter can be used in different applications such as, biological sensing and communication systems.

We present a comparison of different silicon photonics-based wavelength filters for different design criteria (e.g. channel spacing, number of channels, ...) and different performance metrics (e.g. insertion loss or crosstalk ). In this paper we compare only non-resonant filters, or finite-impulse response (FIR) filters, such as Arrayed Waveguide Gratings, Echelle Gratings and higher-order cascades of Mach-Zehnder filters. We derive the strengths and weaknesses from their operational principles and confirm those with experimental data from fabricated devices and extrapolated simulations.

Electro-optically induced waveguides can be used in fiber optic networks for optical power control and the distribution of optical signals transmitted over optical fibers. Reliable operation is ensured with this type of waveguides due to their non-mechanical principle of operation. Their polarization dependent behavior caused by field-induced birefringence effects may limit however their practical applications. We report on a method to reduce the polarization dependent loss in electro-optically induced waveguides with a core made of liquid crystals in isotropic phase. The concept design enables a controlled adjustment of the electric field distribution, which is responsible for inducing and shaping the optical mode, by employing an optimized electrode arrangement. In this new waveguide structure, the TM and TE modes coexist spatially and are guided in a similar way. In order to demonstrate this concept, straight and bending waveguides in 1×1 and 1×2 light input to output configurations have been designed and fabricated. The electrode arrangement and single mode waveguide geometry were optimized using FEM simulations. Bulk silicon micromachining was used to fabricate these waveguides. In particular, the manufactured device consisted of two processed silicon substrates with a liquid crystal layer enclosed in between. Devices tested with varying driving voltage have revealed comparable transmitted power for both TE and TM modes. Very low polarization dependent losses over a more than 20 dB wide dynamic attenuation range have been obtained.

Spiral-waveguide amplifiers in erbium-doped amorphous aluminum oxide are fabricated by RF reactive co-sputtering of 1-μm-thick layers onto a thermally-oxidized silicon wafer and chlorine-based reactive ion etching. The samples are overgrown by a SiO₂ cladding. Spirals with several lengths ranging from 13 cm to 42 cm and four different erbium concentrations between 0.5−3.0×10²⁰ cm^-3 are experimentally characterized. A maximum internal net gain of 20 dB in the small-signal-gain regime is measured at the peak emission wavelength of 1532 nm for two sample configurations with waveguide lengths of 13 cm and 24 cm and erbium concentrations of 2×10²⁰ cm^-3 and 1×10²⁰ cm^-3, respectively. The obtained gain improves previous results by van den Hoven et al. in this host material by a factor of 9. Gain saturation as a result of increasing signal power is investigated. Positive net gain is measured in the saturated-gain regime up to ~100 μW of signal power, but extension to the mW regime seems feasible. The experimental results are compared to a rate-equation model that takes into account migration-accelerated energy-transfer upconversion (ETU) and a fast quenching process affecting a fraction of the erbium ions. Without these two detrimental processes, several tens of dB/cm of internal net gain per unit length would be achievable. Whereas ETU limits the gain per unit length to 8 dB/cm, the fast quenching process further reduces it to 2 dB/cm. The fast quenching process strongly deteriorates the amplifier performance of the Al₂O₃:Er³⁺ waveguide amplifiers. This effect is accentuated for concentrations higher than 2×10²⁰ cm^-3.

We will describe the construction and performance of a prototype high speed, non-mechanically scanned, laser system that is coupled to a custom planar waveguide optical amplifier. The system provides high speed (10 kHz) scanning of <200 far-field resolvable spots, with a path toward <500 spots at 10 kHz demonstrated. An enabling component for this system is the new EO scanner that provides previously unrealizable performance such as sub-millisecond scanning, full 2-D operation with only three control electrodes, fully refractive (no side-lobes) scanning, no blind spot within the field of view (FOV), and a large continuous scan angle. Scanners with near perfect Gaussian output beams, throughputs greater than 50%, and a 500 × 15o continuous field-of-view will be discussed. Furthermore, a path toward much larger FOVs will also be presented. We will also present the design and construction of custom planar waveguide amplifiers to which our EO scanner can be free space end-fire coupled. The amplifiers and scanners were designed for operation at 1.645 microns. This will enable long-range, eye-safe LADAR and sensing applications, such as CH₄ sensors.

Rare-earth ion doped KY(WO₄)₂ amplifiers are proposed to be a good candidate for many future applications by benefiting from the excellent gain characteristics of rare-earth ions, namely high bit rate amplification (<Tbps) with low noise figure (<5-6 dB). However, KY(WO₄)₂ optical waveguide amplifiers based on rare-earth ions were conventionally fabricated on layers overgrown onto undopedKY(WO₄)₂ substrates. Such amplifiers exhibit a refractive index contrast between the doped and undoped layer of typically <0.02, leading to large devices not suited for the high degree of integration required in photonic applications. Furthermore, the large mode diameter in the waveguide core requires high pump input powers to fully invert the material. In this study, we experimentally demonstrate high index contrast waveguides in crystalline KY(WO₄)₂, compatible with the integration onto passive photonic platforms. Firstly, a layer of KY(WO₄)₂ is transferred onto a silicon dioxide substrate using bonding with UV curable optical adhesive. A subsequent polishing step permits precise control of the transferred layer thickness, which defines the height of the waveguides. Small-footprint (in the order of few microns) high index contrast waveguides were patterned using focused ion beam milling. When doped with rare-earth ions, for instance, Er³⁺ or Yb³⁺, such high contrast waveguides will lead to very efficient amplifiers, in which the active material can be efficiently pumped by a confined mode with very good overlap with the signal mode. Consequently, lower pump power will be required to obtain same amount of gain from the amplifier leading to power efficient devices.

We successfully fabricate polymer waveguides with Europium-Aluminum (Eu-Al) polymer composite core using the Mosquito method that utilizes a microdispenser for realizing a compact waveguide optical amplifiers and lasers. Rareearth (RE) ions are widely used as the gain medium for fiber lasers and optical fiber amplifiers. However, high concentration doping of rare-earth-ion leads to the concentration quenching resulting in observing less gain in optical amplification. For addressing the concentration quenching problem, a rare-earth metal (RE-M) polymer composite has been proposed by KRI, Inc. to be a waveguide core material. Actually, 10-wt% RE doping into organic polymer materials was already achieved. Hence, realization of compact and high-efficiency waveguide amplifiers and lasers have been anticipated using the RE-M polymer composite. In this paper, a microdispenser is adopted to fabricate a Eu-doped polymer waveguide. Then, it is experimentally confirmed that the low-loss waveguides are fabricated with a high reproducibility. Optical gain is estimated by measuring the amplified spontaneous emission using the variable stripe length method. The fabricated waveguide exhibits an optical gain as high as 7.1 dB/cm at 616-nm wavelength.

Recent progress on polymer-based photonic devices and hybrid photonic integration technology using InP-based active components is presented. High performance thermo-optic components, including compact polymer variable optical attenuators and switches are powerful tools to regulate and control the light flow in the optical backbone. Polymer arrayed waveguide gratings integrated with InP laser and detector arrays function as low-cost optical line terminals (OLTs) in the WDM-PON network. External cavity tunable lasers combined with C/L band thinfilm filter, on-chip U-groove and 45° mirrors construct a compact, bi-directional and color-less optical network unit (ONU). A tunable laser integrated with VOAs, TFEs and two 90° hybrids builds the optical front-end of a colorless, dual-polarization coherent receiver. Multicore polymer waveguides and multi-step 45°mirrors are demonstrated as bridging devices between the spatialdivision- multiplexing transmission technology using multi-core fibers and the conventional PLCbased photonic platforms, appealing to the fast development of dense 3D photonic integration.

In order to achieve a high refractive index contrast for air-suspended photonic devices, we present a method for laminating thin polymer films onto structured polymer layers that exhibit an air cavity. By using a flat PDMS stamp, polymer films can be transferred over areas of several hundred square microns. On top of the air-suspended slab a second layer of photoresist can be spun and subsequently every desired photonic structure can be defined by using standard photolithography. Here, to demonstrate the feasibility of our lamination method for polymer photonic devices, we present optical modeling and experimental results of air-suspended single mode rib waveguides. Waveguiding is shown for visible and infrared light and a beam profile for λ = 1550 nm is presented that underpins single mode behavior of the rib waveguide.

Surface plasmons polaritons have drawn significant attention in recent years not only thanks to their capability of confining the field in the dielectric/metal interface, but also thanks to their potential to produce highly efficient thermooptical or electro-optical devices such as modulators and switches due to the presence of the metal layer amidst the electromagnetic field. However, the high confinement comes at the cost of high propagation losses due to the metal’s highly absorptive nature at visible and near-IR wavelengths. In order for plasmonic devices to find a widespread use in integrated optics, an advantage over dielectric waveguides needs to be found that justifies their utilization. In this work, we present an application in which metallic waveguides perform better than their dielectric counterparts. By adding a thin metallic layer underneath the waveguide core, the total bend losses (dB/90° are reduced with respect to the bend losses of the equivalent dielectric structure without the metallic layer for a range of radii from 35 µm down to 1 µm. The results show a dramatic reduction of total bend losses in TE-polarization with values as low as 0.02 dB/90° bend for radii between 6 and 13 µm. The mechanism for the reduction of bend losses is the shielding action of the metal layer, which prevents the field to leak into the substrate. In this paper, both detailed theoretical calculations as well as experimental results for SU-8 channel waveguides will be presented.

A fully static OCT device is proposed. The glass integrated optic technology is used to have a large Fourier interferogram along an edge of the glass chip bonded on CCD linear detector array without protective glass window. After having described the system principles, first measurements will be presented. For that an optical signal coming from a SLED is divided in two equal parts injected respectively in a reference input and a probe input. It will be demonstrated that an optical phase difference measurement close to 600µm in the air can be achieved with an optical contrast of 30dB.

Waveguide morphology, as well as etched surface, is one of the most important factors deciding the performance of optical waveguide devices. In this work, we present a combination using photoresist/aluminum bilayer mask for the ICP etching of PZT (Pb(Zr1-xTix)O3) thin films. The etching results of PZT thin films with different etching methods and various etching conditions were investigated. It was found that using ICP in 30/10sccm CHF3/Ar mixture and 3Pa could help reduce the defects and contaminations on the etched surface of PZT thin films. Compared with 250W/60W dual- electrode ICP etching, a more vertical etch profile of PZT waveguide could be obtained through 100W single-electrode ICP etching under the optimal conditions.

Waveguide-resonator systems are particularly useful for the development of several integrated photonic devices, such as tunable filters, optical switches, channel drop filters, reflectors, and impedance matching elements. In this paper, we introduce nanoscale devices based on plasmonic coaxial waveguide resonators. In particular, we investigate threedimensional nanostructures consisting of plasmonic coaxial stub resonators side-coupled to a plasmonic coaxial waveguide. We use coaxial waveguides with square cross sections, which can be fabricated using lithography-based techniques. The waveguides are placed on top of a silicon substrate, and the space between inner and outer coaxial metals is filled with silica. We use silver as the metal. We investigate structures consisting of a single plasmonic coaxial resonator, which is terminated either in a short or an open circuit, side-coupled to a coaxial waveguide. We show that the incident waveguide mode is almost completely reflected on resonance, while far from the resonance the waveguide mode is almost completely transmitted. We also show that the properties of the waveguide systems can be accurately described using a single-mode scattering matrix theory. The transmission and reflection coefficients at waveguide junctions are either calculated using the concept of the characteristic impedance or are directly numerically extracted using full-wave three-dimensional finite-difference frequency-domain simulations.

Titanium dioxide (TiO2) ring resonators based on slot-waveguides were designed, fabricated and characterized for operating wavelengths in the visible and near infrared regions. The fabrication methods include atomic layer deposition (ALD), electron beam lithography (EBL) and reactive ion etching (RIE). The required narrow slot width (30 nm) was achieved by using a conformal ALD re-coating method, i.e., a feature size reduction technique, after the final etching step. The quality factors of the device were estimated to be 626 at 664 nm wavelength and 3446 at 1516 nm wavelength. The results show that the ALD-TiO₂ is a promising platform for sensing applications for visible wavelengths.

In this work, we present fabrication and measurement results of an As₂S₃-on-LiNbO₃ ring resonator waveguide and sidewall grating cavity waveguide. The nonlinear tuning capability is demonstrated on a fabricated ring resonator waveguide by injecting the signal-pump optical power into the device and observing the nonlinear phase shift. The nonlinear tunability of our hybrid As₂S³-on-LiNbO₃ grating cavity waveguide is numerically analyzed.

Femtosecond laser microprocessing is a direct, maskless fabrication technique that has attracted much attention in the past 10 years due to its unprecedented versatility in the 3D patterning of transparent materials. Two common modalities of femtosecond laser microfabrication include buried optical waveguide writing and surface laser ablation, which have been applied to a wide range of transparent substrates including glasses, polymers and crystals. In two photon polymerization, a third modality of femtosecond laser fabrication, focused femtosecond laser pulses drive photopolymerization in photoresists, enabling the writing of complex 3D structures with submicrometer resolution. In this paper, we discuss several microdevices realized by these diverse modalities of femtosecond laser microfabrication, for applications in microfluidics, sensing and quantum information.

In micro-analytical chemistry and biology applications, droplet microfluidic technology holds great promise for efficient lab-on-chip systems where higher levels of integration of different stages on the same platform is constantly addressed. The possibility of integration of opto-microfluidic functionalities in lithium niobate (LiNbO₃) crystals is presented. Microfluidic channels were directly engraved in a LiNbO₃ substrate by precision saw cutting, and illuminated by optical waveguides integrated on the same substrate. The morphological characterization of the microfluidic channel and the optical response of the coupled optical waveguide were tested. In particular, the results indicate that the optical properties of the constituents dispersed in the fluid flowing in the microfluidic channel can be monitored in situ, opening to new compact optical sensor prototypes based on droplets generation and optical analysis of the relative constituents.

We present a new method to form liquid-core optofluidic waveguides inside hydrophobic silica aerogels. Due to their unique material properties, aerogels are very attractive for a wide variety of applications; however, it is very challenging to process them with traditional methods such as milling, drilling, or cutting because of their fragile structure. Therefore, there is a need to develop alternative processes for formation of complex structures within the aerogels without damaging the material. In our study, we used focused femtosecond laser pulses for high-precision ablation of hydrophobic silica aerogels. During the ablation, we directed the laser beam with a galvo-mirror system and, subsequently, focused the beam through a scanning lens on the surface of bulk aerogel which was placed on a three-axis translation stage. We succeeded in obtaining high-quality linear microchannels inside aerogel monoliths by synchronizing the motion of the galvo-mirror scanner and the translation stage. Upon ablation, we created multimode liquid-core optical waveguides by filling the empty channels inside low-refractive index aerogel blocks with highrefractive index ethylene glycol. In order to demonstrate light guiding and measure optical attenuation of these waveguides, we coupled light into the waveguides with an optical fiber and measured the intensity of transmitted light as a function of the propagation distance inside the channel. The measured propagation losses of 9.9 dB/cm demonstrate the potential of aerogel-based waveguides for efficient routing of light in optofluidic lightwave circuits.

Processing ultra-fast optical signals without optical/electronic conversion is in demand and time-to-space conversion has been proposed as an effective solution. We have designed and fabricated an arrayed-waveguide grating (AWG) based optical spectrum control circuit (OSCC) using silica planar lightwave circuit (PLC) technology. This device is composed of an AWG, tunable phase shifters and a mirror. The principle of signal processing is to spatially decompose the signal’s frequency components by using the AWG. Then, the phase of each frequency component is controlled by the tunable phase shifters. Finally, the light is reflected back to the AWG by the mirror and synthesized. Amplitude of each frequency component can be controlled by distributing the power to high diffraction order light. The spectral controlling range of the OSCC is 100 GHz and its resolution is 1.67 GHz. This paper describes equipping the OSCC with optical coded division multiplex (OCDM) encoder/decoder functionality. The encoding principle is to apply certain phase patterns to the signal’s frequency components and intentionally disperse the signal. The decoding principle is also to apply certain phase patterns to the frequency components at the receiving side. If the applied phase pattern compensates the intentional dispersion, the waveform is regenerated, but if the pattern is not appropriate, the waveform remains dispersed. We also propose an arbitrary filter function by exploiting the OSCC’s amplitude and phase control attributes. For example, a filtered optical signal transmitted through multiple optical nodes that use the wavelength multiplexer/demultiplexer can be equalized.

Arrayed-waveguide gratings (AWG) are key devices in optical communication systems using wavelength division multiplexing (WDM), and it is essential that these AWGs are low-loss. In this paper, we propose low-loss segmented joint structures between the slab waveguide and the waveguide array in an AWG. The effectiveness of these structures is confirmed by the measurement results. In addition, improvements in the loss uniformity can be obtained by utilizing mode converting segmented structures between the waveguide array and the slab waveguide on the output side. Moreover, the passband can be flattened by employing such a structure between the input and slab waveguides. These structures were designed using the same simple calculation and optimization method. Using these optimized structures, the transmittance was improved by 17%, the largest difference in insertion loss was reduced by 1.93 dB, and the 1-dB bandwidth was extended by 20%. These structures can be fabricated with ordinary planar lightwave circuit (PLC) technologies without the need for special fabrication processes.

In this paper, we have theoretically analyzed using a finite-difference time domain (FDTD) methods and realized a high sensitive triangular ring resonator sensor based on the total internal reflection (TIR) mirror with a thin metal film for surface plasmon resonance (SPR) phenomenon. One of advantages is a high sensitivity with large phase variation at TIR mirror facet with SPR. Previously, the sensing region of the general ring resonator sensor is located on the cladding region or upper core region. However, the triangular ring resonator has a very high sensitivity using the sensing region of the TIR mirror facet, because the length of the evanescent field at TIR mirror is longer than the evanescent field length at the cladding region. Another is a high Q-factor by the round-trip loss compensation through an active medium in the waveguide. Proposed sensor also has an integrated light source using an InP-based semiconductor optical amplifier. The sensitivity of triangular ring resonator with SPR is extremely enhanced by large phase shift at TIR mirror facet on SPR. Optimized metal thickness is a 33.4 nm at the SPR angle of 22.92 degree. The simulation result of the sensitivity for the triangular ring resonator sensor with SPR is 4.2×10⁴ nm/RIU using by FDTD method. To measure the biosensor, we used an antigen/antibody reaction.

We propose a 650/1550nm wavelength Mux/DeMux for SS-OCT system based on silica-on-silicon (SoS), in which mixing red/infrared lightbeams can be fully separated at low insert loss through special cascaded multimode interference (MMI) structure. Each independent lightbeam is entered into its respective channel by selecting proper width and length of the MMI. By using of Finite Difference Beam Propagation Method (FD-BPM), the Mux/DeMux is optimally designed in size of 1×0.1cm², working at 650nm and 1550nm simultaneously. The results show the degrees of separation between two lightwaves are super high, loss of infrared light is less than 0.5dB and 1dB, and its output power stability is less than 0.25dB and 0.8dB, in 1510nm -1570nm and in 1500nm -1600nm, respectively. The Mux/DeMux can be used in SS-OCT PIC based on SoS.

Integrated optical Mach-Zehnder interferometers (MZI) can be used as high sensitivity sensors through the interaction of the evanescent field of the waveguide with liquids or gases surrounding the sensor. We present here the design of polymer-based MZIs fabricated by hot-embossing and printing technologies. Simulations of an integrated MZI system with regard to variations of the waveguide cross-section and the refractive indices of the core layer are carried out to guarantee single mode behavior and optimize high sensitivity to external refractive index changes of analytes. The simulation of propagation losses induced by the Y-coupleres is also presented. Furthermore, transmission as a function of different interaction window lengths are also simulated on the entire MZI structure using a mixture of water and ethanol as an analyte on the sensing arm. Finally, we calculate the coupling efficiency of a laser diode into a tapered waveguide and estimate that a value of 30% is possible.

In this work, we present fabrication and measurement of sidewall Bragg gratings in chalcogenide arsenic tri-sulfide (As2S3) on titanium-diffused lithium niobate (Ti:LiNbO3) channel waveguides. The transfer matrix method was used to analyze the temporal and spectral response of the sidewall gratings in the mid-infrared. The waveguide sidewall Bragg gratings were fabricated by electron-beam lithography (EBL), metal liftoff and subsequent reactive-ion etching (RIE). Insertion loss of the mid-infrared Ti:LiNbO3 optical waveguides were measured at ~2 dB and the propagation loss was estimated to be 0.45 dB/cm. Configuration of an optical low-coherence interferometer that is capable of characterizing the mid-infrared sidewall grating-based devices was experimentally implemented and preliminary results from fiber Bragg gratings are presented.

Utilizing T-band (1000 nm to 1260 nm) for optical communications is promising for short reach, and large capacity networks, such as data centers or access networks. It is feasible to use this with low-cost coarse wavelength division multiplexing (WDM). However, a tunable wavelength light source is necessary for such applications. In this paper, we propose a new configuration for an external cavity laser, which uses a silica-based arrayed waveguide grating (AWG) for the wavelength selecting element. The external cavity laser consists of a gain chip with high reflection (HR) and anti-reflection (AR) coated facets, coupling lenses, an AWG with AR/HR coatings, and an output fiber. The AWG has 17 connection ports, which correspond to 17 wavelengths with a channel spacing of 1.67 nm. The width of the connection port waveguides was optimized to achieve high coupling efficiency. The AWG chip size is 15 mm x 30 mm. The active layer in the gain chip has InAs quantum dots. The spontaneous emission 3-dB bandwidth was 48 nm (1108 nm to 1156 nm) when a current of 150 mA was injected into the gain chip. The lasing wavelength of the external cavity laser was successfully tuned from 1129.9 nm to 1154.4 nm by selecting the connection ports of the AWG. The typical threshold current was about 130 mA.

Determination of Organic compound concentration in water – is an imperative key to the control of water quality since it provide important information on pollution control of water supply. This work propose an optical sensor system where the organic compound concentration in water is determined using LED light(280nm). The absorbance was quantified according to the high, low and fine concentration of organic compound by means of linear regression modeling.

Directive optical leaky wave antennas (OLWAs) with tunable radiation pattern are promising integrated optical modulation and scanning devices. OLWAs fabricated using CMOS-compatible semiconductor planar waveguide technology have the potential of providing high directivity with electrical tunability for modulation and switching capabilities. We experimentally demonstrate directive radiation from a silicon nitride (Si₃N₄) waveguide-based OLWA. The OLWA design comprises 50 crystalline Si perturbations buried inside the waveguide, with a period of 1 μm, each with a length of 260 nm and a height of 150 nm, leading to a directive radiation pattern at telecom wavelengths. The measured far-field radiation pattern at the wavelength of 1540 nm is very directive, with the maximum intensity at the angle of 84.4° relative to the waveguide axis and a half-power beam width around 6.2°, which is consistent with our theoretical predictions. The use of semiconductor perturbations facilitates electronic radiation control thanks to the refractive index variation induced by a carrier density change in the perturbations. To assess the electrical modulation capability, we study carrier injection and depletion in Si perturbations, and investigate the Franz-Keldysh effect in germanium as an alternative way. We theoretically show that the silicon wire modulator has a -3 dB modulation bandwidth of 75 GHz with refractive index change of 3×10^-4 in depletion mode, and 350 MHz bandwidth with refractive index change of 1.5×10^-2 in injection mode. The Franz-Keldysh effect has the potential to generate very fast modulation in radiation control at telecom wavelengths.