Bragg filters stand as a key building blocks of the silicon-on-insulator (SOI) photonics platform, allowing the implementation of advanced on-chip signal manipulation. However, achieving narrowband Bragg filters with large rejection levels is often hindered by fabrication constraints and imperfections. Here, we present a new generation of high-performance Bragg filters that exploit subwavelength and corrugation symmetry engineering to overcome bandwidth-rejection trade-off in state-of-the-art implementations. We experimentally show flexible control over the width and depth of the Bragg resonance, unlocking new tools for the implementation of notch filters with arbitrary bandwidth and rejection level. These results pave the way for the implementation of high-performance on-chip wavelength filters with a great potential for nonlinear-based applications, e.g. next generation Si-based photon-pair sources for quantum photonic circuits.
Nanophotonic components operate in the few-photon regime, thus their experimental characterization calls for photon-counting techniques, at least in the threshold region, and requires adequate laser models to interpret the observations.
While the photon statistics of (macroscopic) Class A  lasers is well understood and can be readily reconstructed from the zero-delay second order autocorrelation (g(2)(0)), the memory effects introduced by the slow material response of semiconductor-based devices (Class B ) and the sensitivity of nanolasers to spontaneous emission  require a more careful approach. The latter induces a spontaneous spiking dynamics , near threshold, resulting in values of g(2) larger than those expected even for a chaotic signal, and growing without bounds as the duration of the spikes decreases.
Currently available laser models appear unable to predict such a behaviour, due to an inadequate treatment of the contribution of spontaneous emission, and, since the Probability Density Function (PDF) collects into a statistical distribution the state of the system, its predictions fail when the dynamics is not reproduced by the model from which it is derived. Thus, contrary to the usual assumption, the validity of the photon statistics of macroscopic Class B devices  must be reconsidered as the cavity volume is reduced.
We investigate the influence of the cavity size on a commercial VCSEL microlaser with a moderate fraction of spontaneous emission coupled into the lasing mode (beta~0.0001), which represents a happy compromise between a large enough cavity size to detect the dynamics while capturing the self-spiking typical of very small lasers. The autocorrelation (g(2)(0)) is both computed from the intensity time series with a fast (10 GHz) photodetector and deduced from the measured coincidences in arrival times of a photon counting apparatus (TAC with 15 ps timing resolution) in Hanbury-Brown & Twiss (HBT) configuration. We observe values of g(2)(0) up to 2.2, which would produce exponentially decaying distributions if interpreted through the current models . Instead, the experimental PDF, reconstructed from the time series, matches the generic distributions for class B lasers even for the maximum value of g(2)(0).
We therefore conclude that these two techniques cannot be considered as providing equivalent information if only the second order moment g(2) of the distribution is considered, and that new theoretical work is needed on the photon statistics of small-sized Class-B lasers.
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We report an original all-optical synchronization scheme suitable for a quantum relay based experiments at telecom wavelengths. After discussing the entangled photon sources’ performances, we validate our scheme by performing a two-photon interference at the relay station.
We discuss the hybrid integration of multiple components for the production of telecom band single photon sources. We implement four, on-chip, waveguide channels capable of producing four spatially separated collinear pairs of single photons. Using laser inscribed waveguide circuits and point-by-point bre Bragg gratings (FBG), we interface, separate and lter generated photon pairs. We propose using fast switches to actively route multiple heralded single photons to a single output producing an enhanced rate while maintaining a xed noise level.
Periodically poled lithium niobate waveguides (PPLN/W) are considered to be one of the most useful toolboxes for
enabling quantum communication experiments. Thanks to the high optical confinement over longer lengths than in bulk
configurations (a few cm in our case), such structures provide highly efficient non-linear interactions, i.e., in parametric
downconversion, or sum and difference frequency generation regimes. Within the framework of long-distance quantum
communication at telecom wavelengths, PPLN/Ws have therefore been proved to be a key ingredient for building ultrabright
sources of time-bin, as well as polarization entangled photons, and for photonic quantum interfaces providing
coherent wavelength conversions from telecom to visible wavelength range, and conversely. During the presentation, we
will discuss some recent experimental advances regarding polarization entanglement sources and quantum interfaces.
We report on a guided wave asynchronous heralded photon source based on the creation of non-degenerate photon pairs by spontaneous parametric down conversion in a Periodically Poled Lithium Niobate waveguide. We show that using the signal photon at 1310\nm as a trigger, a gated detection process permits announcing the arrival of single photons at 1550nm at the output of a single mode optical fiber with a high probability of 0.37. At the same time the multi-photon emission probability is reduced by a factor of 10 compared to poissonian light sources.