Showing papers by "Guy Millot published in 2023"
TL;DR: In this paper , the authors reported the observation of Rayleigh-Jeans thermalization of light waves to negative-temperature equilibrium states, where the optical wave relaxes to the equilibrium state through its propagation in a multimode optical fiber-i.e., in a conservative Hamiltonian system.
Abstract: Although the temperature of a thermodynamic system is usually believed to be a positive quantity, under particular conditions, negative-temperature equilibrium states are also possible. Negative-temperature equilibriums have been observed with spin systems, cold atoms in optical lattices, and two-dimensional quantum superfluids. Here we report the observation of Rayleigh-Jeans thermalization of light waves to negative-temperature equilibrium states. The optical wave relaxes to the equilibrium state through its propagation in a multimode optical fiber-i.e., in a conservative Hamiltonian system. The bounded energy spectrum of the optical fiber enables negative-temperature equilibriums with high energy levels (high-order fiber modes) more populated than low energy levels (low-order modes). Our experiments show that negative-temperature speckle beams are featured, in average, by a nonmonotonic radial intensity profile. The experimental results are in quantitative agreement with the Rayleigh-Jeans theory without free parameters. Bringing negative temperatures to the field of optics opens the door to the investigation of fundamental issues of negative-temperature states in a flexible experimental environment.
3 citations
25 May 2023
TL;DR: In this article , the frequency dependence of the velocity in a transparent medium was measured using energy-time entangled photons, using the visibility of two-photon fringes recorded in a free evolution regime.
Abstract: Since the first proof-of-principle experiments 25 years ago, quantum metrology has matured from fundamental concepts to versatile and powerful tools in a large variety of research branches, such as gravitational-wave detection, atomic clocks, plasmonic sensing, and magnetometry. At the same time, two-photon interferometry, which underpins the possibility of entanglement to probe optical materials with unprecedented levels of precision and accuracy, holds the promise to stand at the heart of innovative functional quantum sensing systems. We report a novel quantum-based method for measuring the frequency dependence of the velocity in a transparent medium, i.e, the chromatic dispersion (CD). This technique, using energy-time entangled photons, allows straightforward access to CD value from the visibility of two-photon fringes recorded in a free evolution regime. In addition, our quantum approach features all advantages of classical measurement techniques, i.e, flexibility and accuracy, all in a plug-and-play system.
TL;DR: In this article , the authors present an approach based on a gradual and calibrated adjustment of the system configuration, which employs efficient parameter routes to reach well-defined multipulse regimes, and they show that once the mode-locking threshold is reached, they can adjust the laser parameters gradually to force the evolution of the laser dynamics towards multipulse structures with fewer distortion in their intensity profiles.
Abstract: Important ongoing research on mode-locked fiber lasers aims at developing new types of multisoliton regimes, such as soliton molecules, molecular complexes, or soliton crystals. The on-demand generation of such multipulse structures is a major challenge, whereas experiments generally involve a tedious trial-and-error adjustment of the laser parameters. Here we present an approach based on a gradual and calibrated adjustment of the system configuration, which employs efficient parameter routes to reach well-defined multipulse regimes. Our numerical simulations show that once the mode-locking threshold is reached, we can adjust the laser parameters gradually to force the evolution of the laser dynamics towards multipulse structures with fewer distortion in their intensity profiles, which are accessible at reduced pump power levels.
TL;DR: In this paper , the authors present the simulation, fabrication, and characterization of large area microstructured fiber tapers which enable broadband phasematching conditions of the four wave mixing process.
Abstract: Abstract We present the simulation, fabrication, and characterization of large area microstructured fiber tapers which enables broadband phasematching conditions of the four wave-mixing process. These silica-based tapers are intended to serve as a nonlinear gain medium for intense and high average power Fiber Optical Parametric Chirped Pulse Amplifier emitting at 2 $$\upmu \hbox {m}$$ μ m and strongly pumped at Yb wavelength. Different geometries (tapered/untapered, aspect ratio, etc.) are fabricated, analyzed and their broadening properties—key for supporting ultrashort pulses amplification—are compared and discussed. The characterization of nonlinear gain bandwidth of the tapers relies on a tunable source of stochastic pulses based on tunable amplified spontaneous emission in Yb-doped amplifiers. The strong overshoots of this source allows degenerate four-wave mixing process to occur thus generating broadband incoherent visible signal and mid-infrared idler waves at much lower average power than usually needed with coherent pumping. The idler centered around 1.85 $$\mu$$ μ m is broadened due to zero-dispersion wavelength shift along the taper.
TL;DR: In this article , the complex and extensive spectro-temporal dynamics of stimulated Raman scattering in hollow-core photonic crystal fiber, pumped by a single infrared microchip laser, were demonstrated experimentally.
Abstract: We demonstrate experimentally the complex and extensive spectro-temporal dynamics of stimulated Raman scattering in C O 2 -filled hollow-core photonic crystal fiber, pumped by a single infrared microchip laser; namely, the cascading transient Raman process and self-similar behaviors in the regime of higher-order Stokes wave generation. Our measurements are in good agreement with the numerical simulations based on the nonlinear Schrödinger equation.
TL;DR: In this paper , the authors investigated the effect of disorder on Rayleigh-Jeans thermalization through light propagation in MMFs, over a broad range of kinetic energy (i.e., degree of spatial coherence) of injected speckle beam.