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A quasi-deterministic single-photon source and method of generating single photons on demand are disclosed. The single-photon source includes photon pair generation for generating a heralding and heralded photon in a frequency-correlated photon pair, a single-photon spectrometer adapted to detect the heralding photon and to generate an output signal that is indicative of the frequency of the detected heralding photon, a pulse shaper arrangement for reshaping a broadband pulse, and an optical frequency conversion means for converting, upon irradiation with a reshaped pulse, a heralded photon into a single output photon with deterministic source frequency. The pulse shaper arrangement is configured to select, based on the spectrometer output signal, only frequency components of the broadband pulse that substantially coincide with the heralding photon frequency or with a constant detuning thereof., info:eu-repo/semantics/published

Wavelength conversion processes such as spontaneous parametric down conversion (SPDC) and optical parametric amplification (OPA) are key elements in integrated quantum optics. On-chip integration of these function-alities would allow for increased performance and huge scaling opportunities. However, CMOS-compatible plat-forms such as silicon and silicon nitride (SiN) lack a $chi$(2) nonlinearity due to their inversion symmetry. This work provides a solution by heterogeneously integrating periodically poled lithium niobate (PPLN) onto SiN waveguides through micro-transfer printing (textmuTP) [1]. The textmuTP method is a scalable back-end process, allowing the fabrication of the photonic integrated circuit to remain CMOS-compatible., info:eu-repo/semantics/published

A high-speed modulator on silicon nitride is demonstrated using 2 mm-long micro-transfer printed lithium niobate coupons. This device has a 3-dB bandwidth ANDgt;50GHz, and an insertion loss of 3.3 dB that allowed us to transmit 70 Gb/s., info:eu-repo/semantics/published

Several established photonic platforms lack a nonzero Pockels and nonlinear coefficient. We developed a micro-transfer printing method to heterogeneously integrate thin-film lithium niobate and gallium phosphide with an experimentally shown transfer yield of near-unity., info:eu-repo/semantics/published

In this thesis, we study the general dynamics of two coupled fiber Kerr resonators in different configurations. These are systems composed of two coupled individual parts. We go through a first theoretical and numerical study of the two coupled cavities in a passive-passive configuration. We also undergo a numerical and experimental study of self-pulsing dynamics in two coupled Kerr cavities. This is followed by a purely theoretical study of the excitability of the system near a homoclinic bifurcation. The final chapter is devoted to the so-called Parity-Time symmetric configuration in which one cavity is active and compensates for the inherent losses of the passive cavity., Doctorat en Sciences de l'ingénieur et technologie, info:eu-repo/semantics/nonPublished

info:eu-repo/semantics/published

info:eu-repo/semantics/nonPublished

Second harmonic generation is a topic that attracts a lot of attention in photonics and has many applications (laser, microscopy, ). On the other hand, integrated photonics is constantly emerging and is proving to be very interesting for nonlinear effects. It is therefore not surprising that researchers are bringing these two topics together to unite the best of both. One category of materials suitable for such experiments are therefore III-V materials. These materials have interesting properties for such a topic, such as high second order susceptibility and tunable bandgap.Thus, this thesis aims to gain a better understanding of second harmonic generation in III-V integrated structures., Doctorat en Sciences de l'ingénieur et technologie, info:eu-repo/semantics/nonPublished

Surface enhanced Raman spectroscopy (SERS) and stimulated Raman spectroscopy (SRS) are well established techniques capable of boosting the strength of Raman scattering. The combination of both techniques (surface enhanced stimulated Raman spectroscopy, or SE-SRS) has been reported using plasmonic nanoparticles. In parallel, waveguide enhanced Raman spectroscopy has been developed using nanophotonic and nanoplasmonic waveguides. Here, we explore SE-SRS in nanoplasmonic waveguides. We demonstrate that a combined photothermal and thermo-optic effect in the gold material induces a strong background signal that limits the detection limit for the analyte. The experimental results are in line with theoretical estimates. We propose several methods to reduce or counteract this background., SCOPUS: ar.j, info:eu-repo/semantics/published

In the quest for a more compact and cheaper Raman sensor, photonic integration and plasmonic enhancement are central. Nanoplasmonic slot waveguides exhibit the benefits of SERS substrates while being compatible with photonic integration and mass-scale (CMOS) fabrication. A difficulty in pursuing further integration of the Raman sensor with lasers, spectral filters, spectrometers and interconnecting waveguides lies in the presence of a photon background generated by the excitation laser field in any dielectric waveguide constituting those elements. Here, we show this problem can be mitigated by using a multi-mode interferometer and a nanoplasmonic slot waveguide operated in back-reflection to greatly suppress the excitation field behind the sensor while inducing very little photon background., SCOPUS: ar.j, info:eu-repo/semantics/published

Efficient frequency conversion is crucial for interfacing photons with a variety of quantum systems ranging from matter qubits (color centers, quantum dots, atoms), optical fibers, detectors, that often operate at widely different wavelengths. Frequency conversion is also a resource to process quantum information.1,2 Parametric processes such as sum frequency generation (SFG) and Bragg scattering four wave mixing (BS-FWM) offer a good versatility for such frequency conversion. It is well understood that those nonlinear processes have to be strong enough and satisfy phase matching to achieve a high conversion efficiency. While it is enough to consider those two aspects for moderate conversion efficiency up to 50%, the analysis is a bit more complicated when targeting efficiencies closely approaching unity. We are reviewing the pitfall that must be avoided to indeed reach near unity frequency transduction., SCOPUS: cp.p, info:eu-repo/semantics/published

We report a novel on-chip approach for surface-enhanced Raman spectroscopy (SERS) using a plasmonic slot waveguide. The Raman signal is excited via free-space excitation and is collected by the waveguide. A significant improvement of the signal-to-background-ratio (SBR), as compared to the case of back-scattered Raman spectroscopy with waveguide-mode excitation, is demonstrated using a silicon nitride plasmonic slot waveguide with a 7-mm access waveguide. The flexible adjustment of the incident angle in free space and modification of waveguide geometry enables the further optimization of the pump-to-Stokes conversion efficiency. The combination of high SBR and long access waveguide allows the integration with additional photonics devices (sources, filters, spectrometers) on the same chip., SCOPUS: ar.j, info:eu-repo/semantics/published

info:eu-repo/semantics/published

Nanophotonic waveguide enhanced Raman spectroscopy (NWERS) is a sensing technique that uses a highly confined waveguide mode to excite and collect the Raman scattered signal from molecules in close vicinity of the waveguide. The most important parameters defining the figure of merit of an NWERS sensor include its ability to collect the Raman signal from an analyte, i.e. ANDx201C;the Raman conversion efficiencyANDx201D; and the amount of ANDx201C;Raman backgroundANDx201D; generated from the guiding material. Here, we compare different photonic integrated circuit (PIC) platforms capable of on-chip Raman sensing in terms of the aforementioned parameters. Among the four photonic platforms under study, tantalum oxide and silicon nitride waveguides exhibit high signal collection efficiency and low Raman background. In contrast, the performance of titania and alumina waveguides suffers from a strong Raman background and a weak signal collection efficiency, respectively., SCOPUS: ar.j, info:eu-repo/semantics/published

The aim of this thesis is the introduction of new practical Quantum Random Number Generators and new mathematical techniques to certify the random nature of the numbers, based only on a partial characterisation of the devices. Random numbers have a lot of applications, going from mathematical algorithms and betting games to cryptographic protocols, where random keys are a basic premise for constructing protocols. Random Number Generators of the Quantum type have the advantage that they rely on truly random processes, which are guaranteed to be unpredictable by the laws of physics. This makes them in principle more safe than classical hardware generators and pseudo-random algorithms. In the first part of the thesis, we focus of the task of certifying randomness. We introduce a new framework for certifying generators based on quantum optics and that follow a Prepare-and-Measure setup consisting of a source and a measurement device, such as a laser and a single photon detector. Our framework is called semi-Device-Independent, because the device is left largely uncharacterised, as no assumption is made on the source and the measurement device, except for a single physical assumption on the mean photon number (or the energy) of the states prepared by the source. This approach is very secure and robust because any malfunctioning or imperfections in the generator, such additional classical noise, are automatically taken into account as long as the energy assumption is satisfied. We show that, under an energy constraint, there is a fundamental relation between the amount of correlation between the two devices and the amount of randomness produced during the measurement. We establish this by considering all possible underlying quantum models of the devices, that satisfy the mean photon number constraint. We demonstrate that certain strong correlations indeed cannot be reproduced by an underlying deterministic model and show how to compute the amount of randomness in these ca, Doctorat en Sciences, info:eu-repo/semantics/nonPublished

Plasmonic resonances in metallic nanostructures provide a way for broadband enhanced light-matter interaction in subwavelength regions, which can be used to boost a variety of physical phenomena, notably including Raman scattering. Such nanostructures can be integrated on silicon chips and driven via dielectric waveguides, which may improve the performance of photonic integrated circuits in terms of foot-print, efficiency, sensitivity or power consumption, amongst other figures of merit. Here, we show that an isolated plasmonic nanoantenna can be efficiently integrated into a silicon nitride waveguide to detect surface-enhanced Raman scattering (SERS) spectra from molecular monolayers. We study numerically and experimentally two different configurations, both enabling the recording of Raman spectra at the output: nanoantenna on top of the waveguide and nanoantenna inserted in a subwavelength gap built in the waveguide. We also compare both configurations, which may pave the way toward massive integration of SERS devices for lab-on-a-chip applications., SCOPUS: ar.j, info:eu-repo/semantics/published

A broadband and temperature tolerant liquid- controlled adiabatic waveguide coupler (LCC) is realized. The LCC with silicon nitride (SiN) waveguides is designed to be com- patible with liquids that can be actuated by an electrowetting-on- dielectric (EWOD) system. This proof-of-principle demonstration with manual actuation paves the way towards the realization of non-volatile optical switch systems. A 630 μm long LCC configured as a 1 × 2 switch has a measured insertion loss less than 1.5 dB and a crosstalk less than -14 dB for both bar and cross state over the telecommunication wavelength range 1260 nm to 1630 nm. Furthermore, the LCC is tolerant to variations in temperature. The measured excess insertion loss over the temperature range 21°C to 73°C is less than 0.3 dB for bar and cross state, over the same wavelength range., info:eu-repo/semantics/published