We review a hollow-core anti-resonant reflecting optical waveguide (ARROW) based platform for atom photonics. This platform has been used to demonstrate linear and non-linear spectroscopy and quantum coherence effects in hot rubidium vapor on chip. We discuss several advancements to this platform. All-metal seals significantly improve the lifetime of integrated alkali vapor cells. Additional control beams can be used to produce slower light and to slow down atoms via optical scattering and gradient forces. Specifically, a new technique for slowing atoms on a chip based on a spatially varying AC Stark shift is discussed. Moreover, the planarity of the ARROW waveguide platform lends itself to creating advanced layouts with multiple integrated vapor cells for implementing a variety of photonic device functions.

This work reports for the first time development and experimental study of a laboratory prototype of an atomic clock with stability of 2×10^–11τ ^–1/2 (Allan deviation) over time 1 s < τ < 1000 s (7×10^–13 over 1000 s) on the basis of a coherent population trapping (CPT) resonance in ⁸⁷Rb in a compact spherical cell having 1.3-cm diameter and without any buffer gas. Demonstrated are dependencies of the width of the studied CPT resonance upon the amplitude and modulation frequency of optical frequency difference (3.417 GHz) of a bichromatic circularly polarised pump field. For the first time, a considerable non-linearity was discovered in the dependence upon the reference difference frequency of the spectral position of the CPT resonance when the modulation frequency of the optical frequency difference is varied within a broad range.

The mechanism by which light is slowed through ruby has been the subject of great debate. To distinguish between the two main proposed mechanisms, we investigate the problem in the time domain by modulating a laser beam with a chopper to create a clean square wave. By exploring the trailing edge of the pulsed laser beam propagating through ruby, we can determine whether energy is delayed beyond the input pulse. The effects of a time-varying absorber alone cannot delay energy into the trailing edge of the pulse, as a time-varying absorber can only attenuate a coherent pulse. Therefore, our observation of an increase in intensity at the trailing edge of the pulse provides evidence for a complicated model of slow light in ruby that requires more than just pulse reshaping. In addition, investigating the Fourier components of the modulated square wave shows that harmonic components with different frequencies are delayed by different amounts, regardless of the intensity of the component itself. Understanding the difference in delays of the individual Fourier components of the modulated beam reveals the cause of the distortion the pulse undergoes as it propagates through the ruby.

This paper reports the generation of record low group velocities, large group delays, and high optical confinements in strong apodized fiber Bragg gratings (FBGs). The gratings were fabricated in deuterium-loaded fiber using an 806-nm femtosecond laser and a phase mask to produce strong apodized index-modulation profiles and low internal loss, followed by annealing to reduce residual losses. In a first FBG of this type with a length of ~25 mm and a non-saturated index modulation we measured a group delay–transmission product of 10.4 ns, the highest ever reported. In a stronger, shorter FBG (12.3 mm in length), a group delay of 42 ns was observed, corresponding to a group velocity of only ~290 km/s and a group index of 1020. In a still shorter and therefore lower loss device (~5 mm) we were able to observe the fundamental mode, and infer a Purcell factor as high as 25.5. These exceptional features are made possible in part by the gratings’ strong index modulation (~2x10^-3) and ultra-low single-pass loss (~0.01–0.015 dB/cm).

Coherent Perfect Absorbers (CPAs) are optical cavities which can be described as time-reversed lasers where light waves that enter the cavity, coherently interfere and react with the intra-cavity losses to yield perfect absorption. In contrast to lasers, which benefit from high coherency and narrow spectral linewidths, for absorbers these properties are often undesirable as absorption at a single frequency is highly susceptible to spectral noise and inappropriate for most practical applications. Recently, a new class of cavities, characterized by a spectrally wide resonance has been proposed. Such resonators, often referred to as White Light Cavities (WLCs), include an intra-cavity superluminal phase element, designed to provide a phase response with a slope that is opposite in sign and equal in magnitude to that of light propagation through the empty cavity. Consequently, the resonance phase condition in WLCs is satisfied over a band of frequencies providing a spectrally wide resonance. WLCs have drawn much attention due to their attractiveness for various applications such as ultra-sensitive sensors and optical buffering components. Nevertheless, WLCs exhibit inherent losses that are often undesirable. Here we introduce a simple wideband CPA device that is based on the WLC concept along with a complete analytical analysis. We present analytical and FDTD simulations of a practical, highly compact (12µm), Silicon based WLC-CPA that exhibits a flat and wide absorption profile (40nm) and demonstrate its usefulness as an optical pulse terminator (>35db isolation) and an all optical modulator that span the entire C-Band and exhibit high immunity to spectral noise.

We present an experimental realization of slow and fast light schemes for a few ns long optical pulses that makes use of incoherent interactions in an atomic medium. The combination of such different schemes allows us to demonstrate that the propagation delay acquired in the slow light stage, can be completely recovered in a fast light one. The use of an incoherent interactions scheme makes the control of the propagation dynamics of light pulses easer to realize. Delays up to 13 ns, in slow light regime, and advances up to 500 ps, in fast light regime, are reported when the stages work individually for a 3 ns long pulse. When both stages are switched-on the fast light stage is able to recover a previously induced delay and even to produce an extra advance, with an overall advance up to 1 ns. Since every optical transmission line needs an amplification system to overcome the unavoidable losses, the results suggest the opportunity and perspective of a proper tailoring of the amplification stage for data timing purposes.

Long distance superluminal propagation in optical fibers via cascaded Brillouin lasing oscillation is proposed and experimentally demonstrated. The Gaussian pulses experience negative group-velocity superluminal propagation with the advancement of ~300ns in 20-m single mode fiber.

We study theoretically the lasing properties and the cavity lifetime of super and sub-luminal lasers. We find that obtaining the necessary conditions for superluminal lasing is rather difficult and that laser operating under these conditions are unstable and tend to bi-frequency lasing. We study the relaxation time of power perturbation in super and sub-luminal lasers using a finite-difference-time-domain-tool and present the impact between the lasing power, the group velocity and the dispersion properties of the cavity on the relaxation dynamic of such perturbations.

Silicon photonics has drawn a lot of attention over the last decades, mainly in telecom-related application fields where the nonlinear optical properties of silicon are ignored or minimized. However, silicon’s high χ⁽³⁾ Kerr optical nonlinearity in sub-micron-scale high-confinement waveguides can enable significant improvements in traditional nonlinear devices, such as for wavelength conversion, and also enable some device applications in quantum optics or for quantum key distribution. In order to establish the viability of silicon photonics in practical applications, some big challenges are to improve the optical performance (e.g., optimize nonlinearity or minimize loss) and integration of optics with microelectronics. In this context, we discuss how electronic PIN diodes improve the performance of wavelength conversion in a microring resonator based four-wave mixing device, which achieves a continuous-wave four-wave mixing conversion efficiency of −21.3 dB at 100 mW pump power, with enough bandwidth for the wavelength conversion of a 10 Gbps signal. In the regime of quantum optics, we describe a coupled microring device that can serve as a tunable source of entangled photon pairs at telecommunications wavelengths, operating at room temperature with a low pump power requirement. By controlling either the optical pump wavelength, or the chip temperature, we show that the output bi-photon spectrum can be varied, with implications on the degree of frequency correlation of the generated quantum state.

Although it is widely accepted that information cannot travel faster than the speed of light in vacuum, the behavior of quantum correlations and entanglement propagating through actively–pumped dispersive media has not been thoroughly studied. Here we investigate the behavior of quantum correlations and information in the presence of a nonlinear dispersive gaseous medium. We show that the quantum correlations can be advanced by a small fraction of the correlation time while the entanglement is preserved even in the presence of noise added by phase–insensitive gain. Additionally, although we observe an advance of the peak of the quantum mutual information between the modes, we find that the degradation of the mutual information due to the added noise appears to prevent an advancement of the mutual information’s leading tail. In contrast, we show that both the leading and trailing tails of the mutual information in a slow–light system can be significantly delayed in the presence of four-wave mixing (4WM) and electromagnetically induced transparency.

A signal beam is generated in three and four level-atomic system in hot Rb vapors with N₂ buffer in electromagnetically induced transparency (EIT) conditions by adding a pump-beam deflected within a small angle to the coupling and probe beams. Linewidth below 200 Hz and time delay above 1 msec are reported. It is suggested that the generated signal proprieties offer several advantages over the transmitted ones that are used traditionally in EIT applications.

The coherent effects such as forming “dark states,” optical pumping, and the stimulated Raman adiabatic passage (STIRAP) are studied in the presence of dielectric and/or metalic nanoparticles. It is shown that the “dark states” are still formed but they have more complicated atomic structure, the optical pumping and the STIRAP cannot be employed in the vicinity of plasmonic nanostructures. Also we show difference of the local atomic polarization and the atomic polarization averaged over ensemble of atoms homogeneously spread near nanoparticles.

In this paper, we study the rotation sensitivity of a gyroscope made of a two-dimensional array of coupled resonators consisting of N columns of one-dimensional coupled resonant optical waveguides (CROWs) connected by two bus waveguides, each CROW consisting of M identical ring resonators. We show that the maximum rotation sensitivity of this structure is a strong function of the parity of the number of rows M. For an odd number of rows, and when the number of columns is small, the maximum sensitivity is high, and it is slightly lower than the maximum sensitivity of a single-ring resonator with two input/output waveguides (the case M = N = 1), which is a resonant waveguide optical gyroscope (RWOG). For an even M and small N, the maximum sensitivity is much lower than that of the RWOG. Increasing the number columns N increases the sensitivity of an even-row 2D CROW sublinearly, as N^0.39, up to 30 columns. In comparison, the maximum sensitivity of an RWOG of equal area increases faster, as √N. The sensitivity of the 2D CROW therefore always lags behind that of the RWOG. For a 2×2 CROW, if the spacing between the columns L is increased sufficiently the maximum sensitivity increases linearly with L due to the presence of a composite Mach- Zehnder interferometer in the structure. However, for equal footprints this sensitivity is also not larger than that of a single-ring resonator. Regardless of the number of rows and columns and the spacing, for the same footprint and propagation loss, a 2D CROW gyroscope is not more sensitive than an RWOG.

Active coupled resonator optical waveguide (CROW) structure can significantly enhance the performance of optical gyroscope due to its loss compensation effect and highly dispersive properties. In this paper, we analyze the effect of optical gain and its induced noise, i.e. spontaneous emission noise, on the properties of the active CROWs. A thorough investigation of the impact of various disorder degrees on the performance of the active three dimensional vertically coupled resonators (3D-VCR) gyroscope has been performed. It shows how the disorder interacted with coupling coefficient affects the achievable resolution ΔΩ_min of gyroscope, and the degree of disorder will supplant the propagation loss to become an ultimate limitation. Finally, it is shown that the active 3D-VCR gyroscope (the number of ring, N>6) has better resolution ΔΩ_min than that of the equivalent resonant waveguide optical gyroscope (RWOG).

Self-adaptive interferometry allows measuring small optical phase modulations even in noisy environments and with strongly distorted optical wavefronts. We report two examples of self-adaptive interferometers based on liquid crystals, one obtained by using an optically addressed spatial light modulator, the second one realized by adopting adopting digital holography a CCD-LCOS scheme.

A liquid crystal medium is used to perform nonlinear dynamic holography and is coupled with multimode optical fibers for optical sensing applications. Thanks to the adaptive character of the nonlinear holography, and to the sensitivity of the multimode fibers, we demonstrate that the system is able to perform efficient acoustic wave detection even with noisy signals. The detection limit is estimated and multimode versus monomode optical fiber are compared. Finally, a wavelength multiplexing protocol is implemented for the spatial localization of the acoustic disturbances.

The Cold Atom Laboratory is a multipurpose ultracold gas experiment currently being developed for operation on the international space station. It will have the ability to demonstrate proof-of-principle atom interferometry experiments in space. By using microgravity, atom interferometry has the potential to achieve extremely good performance in sensing and navigation applications. Terrestrial experiments can be used to explore potential challenges and prior to launch. One issue of concern is the release of cold atoms from a magnetic trap into free space. Although the atoms will not fall, they can acquire relatively large velocities due to technical limitations such as stray magnetic fields. This can limit the time available for measurements and thus the atom interferometer performance.

This paper focuses on several key ideas to using atom interferometry to detect rotation within the context of an atom trap or “guide”. I discuss shortcomings of traditional free space light pulse atom interferometry that the advantages of guided light pulse atom interferometry can mitigate and under what conditions that strategy is possible. There is discussion of requirements for the light pulses, and the properties of the waveguide that will be needed for guided atom interferometry to successfully improve on the capability of free space light pulse atom interferometry.

High-quality frequency comb sources like femtosecond-lasers have revolutionized the metrology of fundamental physical constants. The generated comb consists of frequency lines with an equidistant separation over a bandwidth of several THz. This bandwidth can be broadened further to a super-continuum of more than an octave through propagation in nonlinear media. The frequency separation between the lines is defined by the repetition rate and the width of each comb line can be below 1 Hz, even without external stabilization. By extracting just one of these lines, an ultra-narrow linewidth, tunable laser line for applications in communications and spectroscopy can be generated. If two lines are extracted, the superposition of these lines in an appropriate photo-mixer produces high-quality millimeter- and THz-waves. The extraction of several lines can be used for the creation of almost-ideally sinc-shaped Nyquist pulses, which enable optical communications with the maximum-possible baud rate. Especially combs generated by low-cost, small-footprint fs-fiber lasers are very promising. However due to the resonator length, the comb frequencies have a typical separation of 80 – 100 MHz, far too narrow for the selection of single tones with standard optical filters. Here the extraction of single lines of an fs-fiber laser by polarization pulling assisted stimulated Brillouin scattering is presented. The application of these extracted lines as ultra-narrow, stable and tunable laser lines, for the generation of very high-quality mm and THz-waves with an ultra-narrow linewidth and phase noise and for the generation of sinc-shaped Nyquist pulses with arbitrary bandwidth and repetition rate is discussed.

The transfer of ultra-stable frequencies between distant laboratories is required by many applications in time and frequency metrology, fundamental physics, particle accelerators and astrophysics. Optical fiber links have been intensively studied for a decade and brought the potential to transfer frequency with a very high accuracy and stability thanks to an active compensation of the propagation noise. We are currently developing an optical metrological network using the fibers of the French National Research and Education Network. Using the so-called dark-channel approach, the ultrastable signal is copropagating with data traffic using wavelength division multiplexing. Due to significant reflections and losses along the fibers, which cannot be compensated with amplifiers, we have developed some repeater stations for the metrological signal. These remotely-operated stations amplify the ultrastable signal and compensate the propagation noise. The link is thus composed of a few cascaded spans. It gives the possibility to increase the noise correction bandwidth, which is proportional to the inverse of the fiber length for each span. These stations are a key element for the deployment of a reliable and large scale metrological network. We report here on the implementation of a two-spans cascaded link of 740 km reaching a relative stability of a few 10^-20 after 10³ s averaging time. Extension to longer links and alternative transfer methods will be discussed.