arXiv subjects

Gregoire Beaudoin

Publications and source records attributed to Gregoire Beaudoin.

12 recordsLinked to original sources

arXiv2026

Plasmonic-cavity Modulator for the Mid-IR with a Semi-transparent and Nonlinear Heavily-doped Semiconductor Mirror

We present a free-space plasmonic modulator based on a single heavily-doped semiconductor layer. We investigate its ability to modulate both the linear and nonlinear response at mid-infrared frequencies slightly below the plasma frequency of the semiconductor. We demonstrate electric control of the linear transmittance and reflectance, and of the efficiency of third-harmonic generation with a field-effect gate structure. We discuss further performance optimization of the device in terms of modulation speed and depth towards a fast modulator with very simple active material requirements. Our results establish a viable route toward practical plasmonic modulators and mixers operating in the mid-infrared atmospheric window available for free-space communications at wavelengths between 8 and 12 um.

physics.optics↗

arXiv2025

Mid-infrared integrated resonators on a III-V platform with Q-factors beyond half a million

We demonstrate mid-IR integrated race-track resonators on a III-V semiconductor platform,InGaAs core epitaxially grown on InP. We have performed a complete characterization of the optical propagation losses at wavelength = 4.6 um and wavelength = 8.5 um, two representative wavelengths for the 1st and 2nd atmospheric transparency windows. We measured losses of 1 dB/cm (TE polarization) and 1.3 dB/cm (TM polarization) at 8.5 um. Substantially lower losses, 0.28 dB/cm, were measured at wavelength = 4.6 um (TM polarization). We then implemented racetrack resonators with straight evanescent couplers. We obtained loaded quality factors larger than 600.000 at wavelength = 4.6 um. These results are promising towards the development of non-linear mid-IR integrated devices with Q factors beyond a million, where the onset of stimulated parametric processes could be reachable.

physics.optics↗

arXiv2024

Origin of optical nonlinearity in plasmonic semiconductor nanostructures

The development of nanoscale nonlinear elements in photonic integrated circuits is hindered by the physical limits to the nonlinear optical response of dielectrics, which requires that the interacting waves propagate in transparent volumes for distances much longer than their wavelength. Here we present experimental evidence that optical nonlinearities in doped semiconductors are due to free-electron and their efficiency could exceed by several orders of magnitude that of conventional dielectric nonlinearities. Our experimental findings are supported by comprehensive computational results based on the hydrodynamic modeling, which naturally includes nonlocal effects, of the free-electron dynamics in heavily doped semiconductors. By studying third-harmonic generation from plasmonic nanoantenna arrays made out of heavily n-doped InGaAs with increasing levels of free-carrier density, we discriminate between hydrodynamic and dielectric nonlinearities. As a result, the value of maximum nonlinear efficiency as well as its spectral location can now be controlled by tuning the doping level. Having employed the common material platform InGaAs/InP that supports integrated waveguides, our findings pave the way for future exploitation of plasmonic nonlinearities in all-semiconductor photonic integrated circuits.

physics.optics↗

arXiv2022

Tracking exceptional points above laser threshold

Recent studies on non-Hermitian optical systems having exceptional points (EPs) have revealed a host of unique characteristics associated with these singularities, including unidirectional invisibility, chiral mode switching and laser self-termination, to mention just a few examples. The vast majority of these works focused either on passive systems or active structures where the EPs were accessed below the lasing threshold, i.e. when the system description is inherently linear. In this work, we experimentally demonstrate that EP singularities in coupled semiconductor nanolasers can be accessed and tracked above the lasing threshold, where they become branch points of a nonlinear dynamical system. Contrary to the common belief that unavoidable cavity detuning will impede the formation of an EP, here we demonstrate that this same detuning is necessary for compensating the carrier-induced frequency shift, hence restoring the nonlinear EP in the lasing regime. Furthermore, unlike linear non-Hermitian systems, we find that the spectral location of EPs above laser threshold varies as a function of total pump power and can therefore be continuously tracked. Our work is a first step towards the realization of lasing EPs in more complex laser geometries, and enabling the enhancement of photonic local density of states through non-Hermitian symmetries combined with nonlinear interactions in coupled laser arrays.

physics.optics↗

arXiv2020

Slow propagation of 2 GHz acoustical waves in a suspended GaAs on insulator phononic waveguide

Optoelectronic oscillators have dominated the scene of microwave oscillators in the last few years thanks to their great performances regarding frequency stability and phase noise. However, miniaturization of such a device is an up to date challenge. Recently, devices based on phonon-photon interaction gather a lot of interest thanks to their extreme compactness and working frequency directly in the GHz. In this frame, a still missing element to obtain long-term frequency stability performances is an on-chip delay within the feedback loop. Here, we experimentally show filtering and slow propagation of 2 GHz acoustic waves on a Gallium Arsenide membrane heterogeneously integrated on silicon wafer. By engineering the dispersion of an acoustical waveguide, we evidence a group velocity below 1000 m/s for the mode able to propagate. Thus, an integrated delay implementation is at reach for potential improvement of opto-acoustic devices such as optomechanical oscillators or wireless applications.

physics.app-ph↗

arXiv2019

Photonic crystal nanobeam cavities with optical resonances around 800 nm

We report on the design and the fabrication of 1D photonic crystal (PhC) nanobeam cavities with optical resonances around 800 nm, compatible with Rubidium, Cesium or Argon atomic transitions. The cavities are made of Indium Gallium Phosphide (InGaP) material, a III-V semi-conductor compound which has a large index of refraction ($n \simeq 3.3$) favoring strong optical confinement and small mode volumes. Nanobeam cavities with inline and side coupling have been designed and fabricated, and quality factors up to $2\times 10^4$ have been measured.

physics.optics↗

arXiv2015

Spatiotemporal chaos induces extreme events in an extended microcavity laser

Extreme events such as rogue wave in optics and fluids are often associated with the merging dynamics of coherent structures. We present experimental and numerical results on the physics of extreme events appearance in a spatially extended semiconductor microcavity laser with intracavity saturable absorber. This system can display deterministic irregular dynamics only thanks to spatial coupling through diffraction of light. We have identified parameter regions where extreme events are encountered and established the origin of this dynamics in the emergence of deterministic spatiotemporal chaos, through the correspondence between the proportion of extreme events and the dimension of the strange attractor.

nlin.CD↗

arXiv2014

Spontaneous mirror-symmetry breaking in a photonic molecule

Multi-cavity photonic systems, known as photonic molecules (PMs), are ideal multi-well potential building blocks for advanced quantum and nonlinear optics. A key phenomenon arising in double well potentials is the spontaneous breaking of the inversion symmetry, i.e. a transition from a delocalized to two localized states in the wells, which are mirror images of each other. Although few theoretical studies have addressed mirror-symmetry breaking in micro and nanophotonic systems, no experimental evidence has been reported to date. Thanks to the potential barrier engineering implemented here, we demonstrate spontaneous mirror-symmetry breaking through a pitchfork bifurcation in a PM composed of two coupled photonic crystal nanolasers. Coexistence of localized states is shown by switching them with short pulses. This offers exciting prospects for the realization of ultra-compact, integrated, scalable optical flip-flops based on spontaneous symmetry breaking. Furthermore, we predict such transitions with few intracavity photons for future devices with strong quantum correlations.

physics.optics↗

arXiv2011

Single InAsP/InP quantum dots as telecommunications-band photon sources

The optical properties of single InAsP/InP quantum dots are investigated by spectrally-resolved and time-resolved photoluminescence measurements as a function of excitation power. In the short-wavelength region (below 1.45 $μ$m), the spectra display sharp distinct peaks resulting from the discrete electron-hole states in the dots, while in the long-wavelength range (above 1.45 $μ$m), these sharp peaks lie on a broad spectral background. In both regions, cascade emission observed by time-resolved photoluminescence confirms that the quantum dots possess discrete exciton and multi-exciton states. Single photon emission is reported for the dots emitting at 1.3 $μ$m through anti-bunching measurements.

cond-mat.mtrl-sci↗

arXiv2011

Higher-order photon correlations in pulsed photonic crystal nanolasers

We report on the higher-order photon correlations of a high-$β$ nanolaser under pulsed excitation at room temperature. Using a multiplexed four-element superconducting single photon detector we measured g$^{(n)}(\vec{0})$ with $n$=2,3,4. All orders of correlation display partially chaotic statistics, even at four times the threshold excitation power. We show that this departure from coherence and Poisson statistics is due to the quantum fluctuations associated with the small number of dipoles and photons involved in the lasing process.

physics.optics↗

arXiv2010

Demonstration of coherent emission from high-$β$ photonic crystal nanolasers at room temperature

We report on lasing at room temperature and at telecommunications wavelength from photonic crystal nanocavities based on InAsP/InP quantum dots. Such laser cavities with a small modal volume and high quality factor display a high spontaneous emission coupling factor beta. Lasing is confirmed by measuring the second order autocorrelation function. A smooth transition from chaotic to coherent emission is observed, and coherent emission is obtained at 8 times the threshold power.

physics.optics↗

arXiv2008

Time-Resolved characterization of InAsP/InP quantum dots emitting in the C-band telecommunication window

The dynamic response of InAsP quantum dots grown on InP(001) substrates by low-pressure Metalorganic Vapor Phase Epitaxy emitting around 1.55 $μ$m, is investigated by means of time-resolved microphotoluminescence as a function of temperature. Exciton lifetime steadily increases from 1 ns at low temperature to reach 4 ns at 300K while the integrated photoluminescence intensity decreases only by a factor of 2/3. These characteristics give evidence that such InAsP/InP quantum dots provide a strong carrier confinement even at room temperature and that their dynamic response is not affected by thermally activated non-radiative recombination up to room temperature.

cond-mat.mtrl-sci↗