arXiv subjects

Aurelian Loirette-Pelous

Publications and source records attributed to Aurelian Loirette-Pelous.

4 recordsLinked to original sources

arXiv2026

Addressing intramolecular vibrational redistribution in a single molecule through pump and probe surface-enhanced vibrational spectroscopy

The development of accurate tools to characterize Intramolecular Vibrational Redistribution (IVR) is of major interest in chemistry. In this context, surface-enhanced vibrational spectroscopies stand up as well-established techniques to study molecular vibrational lines and populations with a sensitivity that can reach the single-molecule level. However, to date, this possibility has not been fully developed to address IVR. Here, we establish a quantum mechanical framework based on molecular optomechanics that accounts for IVR, and we adopt it to analyze strategies to optimize IVR characterization by surface-enhanced vibrational spectroscopy. In particular, we model two different pump-and-probe configurations where the vibrational pumping is provided either by infrared laser illumination or by Stokes scattering processes in surface-enhanced Raman spectroscopy (SERS). We show for the two pumping configurations the existence of clear signatures on the anti-Stokes SERS spectra of population transfer between coupled vibrational modes in a molecule. Our calculations adopt realistic molecular and SERS parameters, suggesting that these signatures of IVR could be accessible at the single-molecule level within realistic experimental platforms.

physics.optics↗

arXiv2024

Theory of photoluminescence by metallic structures

Light emission by metals at room temperature is quenched by fast relaxation processes. Nevertheless, Mooradian reported in 1969 the observation of photoluminescence by metals pumped by a laser. Strikingly, while it is currently at the heart of many promising applications, this phenomenon is still poorly understood. In this work, we report a theory which reproduces quantitatively previously published experimental data. We first provide a general formula that relates the emitted power for a frequency, direction and polarization state to a sum over all transitions involving matrix elements, electronic distribution of all bands and the Green tensor. We then consider the case of intraband recombination and derive a closed-form expression of the emitted power depending only on macroscopic quantities. This formula, which is a generalization of Kirchhoff's law, answers many of the open questions related to intraband photoluminescence.

physics.optics↗

arXiv2023

Photon Bose-Einstein condensation and lasing in semiconductor cavities

Photon Bose-Einstein condensation and photon thermalisation have been largely studied with molecular gain media in optical cavities. Their observation with semiconductors has remained elusive despite a large body of experimental results and a very well established theoretical framework. We use this theoretical framework as a convenient platform to revisit photon Bose-Einstein condensation in the driven-dissipative regime and compare with the lasing regime. We discuss the thermalisation figures of merit and the different experimental procedures to asses thermalization. We compare the definitions of lasing and condensation thresholds. Finally, we explore the fluctuations of the system and their relation to the different regimes.

cond-mat.quant-gas↗

arXiv2021

Linearized theory of the fluctuation dynamics in 2D topological lasers

We theoretically study the collective excitation modes of a topological laser device operating in a single-mode steady-state with monochromatic emission. We consider a model device based on a two-dimensional photonic Harper-Hofstadter lattice including a broadband gain medium localized on the system edge. Different regimes are considered as a function of the value of the optical nonlinearity and of the gain relaxation time. The dispersion of the excitation modes is calculated via a full two-dimensional Bogoliubov approach and physically interpreted in terms of an effective one-dimensional theory. Depending on the system parameters, various possible physical processes leading to dynamical instabilities are identified and characterized. On this basis, strategies to enforce a stable single-mode topological laser operation are finally pointed out.

physics.optics↗