Stéphane Clemmen

Nonlinear properties of and nonlinear processing in hydrogenated amorphous silicon waveguides

We propose hydrogenated amorphous silicon nanowires as a platform for nonlinear optics in the telecommunication wavelength range. Extraction of the nonlinear parameter of these photonic nanowires reveals a figure of merit larger than 2. It is observed that the nonlinear optical properties of these waveguides degrade with time, but that this degradation can be reversed by annealing the samples. A four wave mixing conversion efficiency of + 12 dB is demonstrated in a 320 Gbit/s serial optical waveform data sampling experiment in a 4 mm long photonic nanowire.

On-chip parametric amplification with 26.5 dB gain at telecommunication wavelengths using CMOS-compatible hydrogenated amorphous silicon waveguides

We present what we believe to be the first study of parametric amplification in hydrogenated amorphous silicon waveguides. Broadband on/off amplification up to 26.5u2009dB at telecom wavelength is reported. Measured nonlinear parameter is 770u2009W(-) m(-1), nonlinear absorption 28u2009W(-1) u2009m(-1), bandgap 1.61u2009eV.

Generation of correlated photons in hydrogenated amorphous-silicon waveguides

We report the first (to our knowledge) observation of correlated photon emission in hydrogenated amorphous-silicon waveguides. We compare this to photon generation in crystalline silicon waveguides with the same geometry. In particular, we show that amorphous silicon has a higher nonlinearity and competes with crystalline silicon in spite of higher loss.

Spontaneous growth of Raman Stokes and anti-Stokes waves in fibers

Using the quantum theory of light, we derive general analytical expressions of Stokes and anti-Stokes spectral photon-flux densities that are spontaneously generated by a single monochromatic pump wave propagating in a single-mode optical fiber. We validate our results by comparing them with experimental data. Limiting cases corresponding to interesting physical situations are discussed.

Self phase modulation in highly nonlinear hydrogenated amorphous silicon

We study self phase modulation in submicron amorphous silicon-on-insulator waveguides. We extract both the real and imaginary part of the nonlinear parameter γ from a 1 cm long waveguide with a cross-section of 500×220nm². The real and imaginary part of the nonlinear parameter are found to be 767W^-1m^-1 and -28W^-1m^-1 respectively. The figure of merit (FOM) is found to be 3.6 times larger than the FOM in crystalline silicon (c-Si).

Low-power inelastic light scattering at small detunings in silicon wire waveguides at telecom wavelengths

When a pump beam is propagating through a silicon nanophotonic waveguide, a very small fraction of the light is scattered to other frequencies. At very low intensity, the amount of scattered light is proportional to the power of the pump beam. We show that the scattering intensity increases linearly within the temperature range 300–575xa0K and that the photon flux decreases as the inverse of the frequency detuning ν over the investigated bandwidth 0.4u2009u2009THz<|ν|<2.5u2009u2009THz. The simplest interpretation of these observations is that the pump beam is scattered on a one-dimensional thermal bath of excitations. Finally, the implications of this scattering process for quantum optics applications of silicon nanophotonic structures are discussed.

Frequency multiplexing for quasi-deterministic heralded single-photon sources

Parametric single-photon sources are wellxa0suited for large-scale quantum networks due to their potential for photonic integration. Active multiplexing of photons can overcome the intrinsically probabilistic nature of these sources, resulting in near-deterministic operation. However, previous implementations using spatial and temporal multiplexing scale unfavorably due to rapidly increasing switching losses. Here, we break this limitation via frequency multiplexing in which switching losses remain fixed irrespective of the number of multiplexed modes. We use low-noise optical frequency conversion for efficient frequency switching and demonstrate multiplexing of three modes. We achieve a generation rate of 4.6u2009×u2009104 photons per second with an ultra-low g(2)(0)u2009=u20090.07 indicating high single-photon purity. Our scalable, all-fiber multiplexing system has a total loss of just 1.3u2009dB, such that the 4.8u2009dB multiplexing enhancement markedly overcomes switching loss. Our approach offers a promising path to creating a deterministic photon source on an integrated chip-based platform.The aim of multiplexing is to boost capabilities of probabilistic single photon sources, but is vexed by rapidly increasing switching losses. Here, the authors propose and implement an in-fiber frequency-multiplexing scheme where total losses are independent of the number of multiplexed modes.

Continuous wave photon pair generation in silicon-on-insulator waveguides and ring resonators: erratum

An error was made which is a basic calculation mistake. We have corrected this error and updated the prospects about ring cavity-based photon pair sources.

Nonlinear optical functions in crystalline and amorphous Silicon-on-Insulator nanowires

Silicon-on-Insulator nanowires provide an excellent platform for nonlinear optical functions in spite of the two-photon absorption at telecom wavelengths. Work on both crystalline and amorphous silicon nanowires is reviewed, in the wavelength range of 1.5 to 2.5 μm.