arXiv subjects

Thibaut Sylvestre

Publications and source records attributed to Thibaut Sylvestre.

17 recordsLinked to original sources

arXiv2024

Ultralow-Noise Optical Parametric Amplifier for Stimulated Raman Scattering Imaging

We present a 40-MHz ultrafast optical parametric amplifier (OPA), tunable from 0.8 to 1 $μ$m, with a relative intensity noise (RIN) matching the shot-noise floor (-160 dB/Hz) above 2 MHz. The OPA is pumped by a 20-W Kerr-lens mode-locked Ytterbium laser and seeded by a a supercontinuum generated in an all-normal-dispersion (ANDi) fiber. With an average output power >1.5 W, this compact and simple scheme is an attractive alternative to synchronously-pumped optical parametric oscillators, especially within the context of stimulated Raman scattering (SRS) imaging. To illustrate the latter, we perform chemical imaging of vinegar droplets in oil by SRS microscopy.

physics.optics↗

arXiv2023

Spin-orbit interaction in nanofiber-based Brillouin scattering

Angular momentum is an important physical property that plays a key role in light-matter interactions such as spin-orbit interaction. Here, we investigate theoretically and experimentally the spin-orbit interaction between a circularly polarized optical (spin) and a transverse vortex acoustic wave (orbital) using Brillouin backscattering in a silica optical nanofiber. We specifically explore the state of polarization of Brillouin backscattering induced by the TR21 torso-radial vortex acoustic mode that carries an orbital angular momentum. Using a full-vectorial theoretical model, we predict and observe two operating regimes for which the backscattered Brillouin signal is either depolarized or circularly polarized depending on the input pump polarization. We demonstrate that when the pump is circularly polarized and thus carries a spin angular momentum, the backscattered signal undergoes a handedness reversal of circular polarization due to optoacoustic spin-orbit interaction and the conservation of overall angular momentum.

physics.optics↗

arXiv2022

Noise in supercontinuum generated using PM and non-PM tellurite glass all-normal dispersion fibers

Intensity fluctuations in supercontinuum generation are studied in polarization-maintaining (PM) and non-PM all-normal dispersion tellurite photonic crystal fibers. Dispersive Fourier transformation is used to resolve the shot-to-shot spectra generated using 225 fs pump pulses at 1.55 μm, with experimental results well reproduced by vector and scalar numerical simulations. By comparing the relative intensity noise for the PM and non-PM cases, supported by simulations, we demonstrate the advantage of the polarization-maintaining property of the PM fibers in preserving low-noise dynamics. We associate the low-noise in the PM case with the suppression of polarization modulation instability.

physics.optics↗

arXiv2020

Cross-Phase Modulation Instability in PM ANDi Fiber-Based Supercontinuum Generation

We demonstrate broadband supercontinuum generation in an all-normal dispersion polarization-maintaining photonic crystal fiber and we report the observation of a cross-phase modulation instability sideband that is generated outside of the supercontinuum bandwidth. We demonstrate this sideband is polarized on the slow axis and can be suppressed by pumping on the fiber's fast axis. We theoretically confirm and model this nonlinear process using phase-matching conditions and numerical simulations, obtaining good agreement with the measured data.

physics.optics↗

arXiv2019

Nanoimprinting and Tapering of Chalcogenide Photonic Crystal Fibers for Cascaded Supercontinuum Generation

Improved long-wavelength transmission and supercontinuum (SC) generation is demonstrated by anti-reflective (AR) nanoimprinting and tapering of chalcogenide photonic crystal fibers (PCF). Using a SC source input spanning from 1-4.2 μm, the total transmission of a 15 μm core diameter PCF was improved from ~53 % to ~74 % by nanoimprinting of AR structures on both input- and output facets of the fiber. Through a combined effect of reduced reflection and red-shifting of the spectrum to 5 μm, the relative transmission of light >3.5 μm in the same fiber was increased by 60.2 %. Further extension of the spectrum to 8 μm was achieved using tapered fibers. The spectral broadening dynamics and output power was investigated using different taper parameters and pulse repetition rates.

physics.optics↗

arXiv2019

Nested-capillary anti-resonant silica fiber with mid-infrared transmission and low bending sensitivity at 4000 nm

We report a silica glass nested capillary anti-resonant nodeless fiber with transmission and low bending sensitivity in the mid-infrared around 4000 nm. The fiber is characterized in terms of transmission over 1700-4200 nm wavelengths, revealing a mid-infrared 3500-4200 nm transmission window, clearly observable for a 12 m long fiber. Bending loss around 4000 nm is 0.5 dB/m measured over 3 full turns with 40 mm radius, going up to 5 dB/m for full turns with 15 mm radius. Our results provide experimental evidence of hollow-core silica fibers in which nested, anti-resonant capillaries provide high bend resistance in the mid-infrared. This is obtained for a fiber with large core diameter of over 60 um relative to around 30 um-capillaries in the cladding, which motivates its application in gas fiber lasers or fiber-based mid-infrared spectroscopy of COx or NxO analytes.

physics.optics↗

arXiv2019

Nonlinear elasticity of silica nanofiber

Optical nanofibers (ONFs) are excellent nanophotonic platforms for various applications such as optical sensing, quantum and nonlinear optics, due to both the tight optical confinement and their wide evanescent field in the sub-wavelength limit. Other remarkable features of these ultrathin fibers are their surface acoustic properties and their high tensile strength. Here we investigate Brillouin light scattering in silica-glass tapered optical fibers under high tensile strain and show that the fundamental properties of elastic waves dramatically change due to elastic anisotropy and nonlinear elasticity for strain larger than 2%. This yields to unexpected and remarkable Brillouin strain coefficients for all Brillouin resonances including surface and hybrid waves, followed by a nonlinear evolution at high tensile strength. We further provide a complete theoretical analysis based on third-order nonlinear elasticity of silica that remarkably agrees with our experimental data. These new regimes open the way to the development of compact tensile strain optical sensors based on nanofibers.

physics.optics↗

arXiv2019

Amplitude noise and coherence degradation of femtosecond supercontinuum generation in all-normal-dispersion fibers

Supercontinuum (SC) generation via femtosecond (fs) pumping in all-normal-dispersion (ANDi) fiber is predicted to offer completely coherent broadening mechanisms, potentially allowing for substantially reduced noise levels in comparison to those obtained when operating in the anomalous dispersion regime. However, previous studies of SC noise typically treat only the quantum noise, typically in the form of one-photon-per-mode noise, and do not consider other technical noise contributions, such as the stability of the pump laser, which become important when the broadening mechanism itself is coherent. In this work, we discuss the influence of the amplitude and pulse length noise of the pump laser, both added separately and combined. We show that for a typical mode-locked laser, in which the peak power and pulse duration are anticorrelated, their combined impact on the SC noise is generally smaller than in isolation. This means that the supercontinuum noise is smaller than the noise of the mode-locked pump laser itself, a fact that was recently observed in experiments but not explained. Our detailed numerical analysis shows that the coherence of ANDi SC generation is considerably reduced on the spectral edges when realistic pump laser noise levels are taken into account.

physics.optics↗

arXiv2018

Brillouin phonon cooling by electro-optic feedback

We theoretically investigate the cooling of a propagating phonon through Brillouin scattering. To that end, we propose to introduce an external viscous force using Brillouin scattering and an electro-optic feedback. Short delays feedback show an efficient control of the Brillouin linewidth whereas long delays can induce Fano-like resonances.

physics.optics↗

arXiv2017

Brillouin spectroscopy of optical microwires

We describe an easy-to-implement technique that allows for a complete experimental characterization of sub-wavelength diameter tapered optical fibers. Our method is based on a direct and fast numerical analysis of the backward Brillouin spectrum measured using a highly sensitive single-ended heterodyne coherent detection. It can be performed in situ without any manipulation nor optical alignment of optical microfibers. Sensitivity as high as a few nanometer for fiber diameter ranging from 500 nm to 1.2 micron is reported. This new method may help for the design and characterization of optical fiber tapers widely used in many applications such as optical sensing, atom trapping, quantum optics, and plasmonics.

physics.optics↗

arXiv2015

Parametric frequency fusion by inverse four-wave mixing

This work reports the experimental observation of a new type of four-wave mixing in which frequency-degenerate weak signal and idler waves are generated by mixing two pump waves of different frequencies in a normally dispersive birefringent optical fiber. This parametric frequency fusion is what we believed the first experimental evidence of inverse four-wave mixing.

physics.optics↗

arXiv2015

Stimulated Brillouin scattering revisited: Strong coupling regime and Rabi splitting

Stimulated Brillouin scattering in optical waveguides is a fundamental interaction between light and acoustic waves mediated by electrostriction and photoelasticity. In this paper, we revisit the usual theory of this inelastic scattering process to get a joint system in which the acoustic wave is strongly coupled to the interference pattern between the optical waves. We show in particular that, when the optoacoustic coupling rate is comparable to the phonon damping rate, the system enters in the strong coupling regime, giving rise to avoided crossing of the dispersion curve and Rabi-like splitting. We further find that optoacoustic Rabi splitting could in principle be observed using backward stimulated Brillouin scattering in sub-wavelength diameter tapered optical fibers with moderate peak pump power.

physics.optics↗

arXiv2015

Cascaded Brillouin lasing in monolithic barium fluoride whispering gallery mode resonators

We report the observation of stimulated Brillouin scattering and lasing at 1550~nm in barium fluoride (BaF$_2$) crystal. Brillouin lasing was achieved with ultra-high quality ($Q$) factor monolithic whispering gallery mode (WGM) mm-size disk resonators. Overmoded resonators were specifically used to provide cavity resonances for both the pump and all Brillouin Stokes waves. Single and multiple Brillouin Stokes radiations with frequency shift ranging from $8.2$ GHz up to $49$ GHz have been generated through cascaded Brillouin lasing. BaF$_2$ resonator-based Brillouin lasing can find potential applications for high-coherence lasers and microwave photonics.

physics.optics↗

arXiv2014

Far detuned mid-infrared frequency conversion via normal dispersion modulation instability in chalcogenide microwire

We report the observation of modulation instability in the mid-infrared spectral region by pumping a hybrid polymer-chalcogenide optical microwire with a femtosecond optical parametric oscillator operating at 2.6 μm. It is further shown that this modulation instability occurs in the normal dispersion regime through negative fourth-order dispersion and leads to far detuned parametric frequency conversion at 2 μm and 3.5 μm, despite the presence of a strong absorption band around 2.8 μm. Stochastic nonlinear Schrödinger equation simulations of mid-infrared modulation instability are in excellent agreement with experiments.

physics.optics↗

arXiv2014

Stimulated Brillouin scattering from surface acoustic waves in sub-wavelength photonic microwires

Brillouin scattering in optical fibres is a fundamental interaction between light and sound with important implications ranging from optical sensors to slow and fast light. In usual optical fibres, light both excites and feels shear and longitudinal bulk elastic waves, giving rise to forward guided acoustic wave Brillouin scattering and backward stimulated Brillouin scattering. In a subwavelength-diameter optical fibre, the situation changes dramatically, as we here report with the first experimental observation of stimulated Brillouin scattering from surface acoustic waves. These Rayleigh-type hypersound waves travel the wire surface at a specific velocity of 3400 m.s$^{\mathrm{-1}}$ and backscatter the light with a Doppler shift of about 6 GHz. As these acoustic resonances are highly sensitive to surface defects or features, surface acoustic wave Brillouin scattering opens new opportunities for various sensing applications, but also in other domains such as microwave photonics and nonlinear plasmonics.

physics.optics↗

arXiv2012

Modeling of octave-spanning Kerr frequency combs using a generalized mean-field Lugiato-Lefever model

A generalized Lugiato-Lefever equation is numerically solved with a Newton-Raphson method to model Kerr frequency combs. We obtain excellent agreement with past experiments, even for an octave-spanning comb. Simulations are much faster than with any other technique despite including more modes than ever before. Our study reveals that Kerr combs are associated with temporal cavity solitons and dispersive waves, and opens up new avenues for the understanding of Kerr comb formation.

physics.optics↗

arXiv2003

Quantum fluctuations and correlations of spatial scalar or multimode vector solitons in Kerr media

We apply the Green's function method to determine the global degree of squeezing and the transverse spatial distribution of quantum fluctuations of solitons in Kerr media. We show that both scalar bright solitons and multimode vector solitons experience strong squeezing on the optimal quadrature. For vector solitons, this squeezing is shown to result from an almost perfect anti-correlation between the fluctuations on the two incoherently-coupled circular polarisations.

quant-ph↗