Geoffrey Gaulier | Searcharxiv

arXiv2024

Open-Path Detection of Organic Vapors via Quantum Infrared Spectroscopy

In recent years, quantum Fourier transform infrared (QFTIR) spectroscopy emerged as an alternative to conventional spectroscopy in the mid-infrared region of the spectrum. By harnessing induced coherence and spectral entanglement, QFTIR offers promising potential for the practical detection of organic gasses. However, little research was conducted to bring QFTIR spectrometers closer to domestic or in-field usage. In this work, we present the first use of a QFTIR spectrometer for open-path detection of multiple interfering organic gases in ambient air. The accurate identification of mixtures of acetone, methanol, and ethanol vapors is demonstrated with a QFTIR spectrometer. We achieved this breakthrough by building a nonlinear Michelson interferometer with 1.7m-long arms to increase the absorption length, coupled with analysis techniques from differential absorption spectroscopy. The evolution of different gasses' concentrations in ambient air was measured through time. These results constitute the first use-case of a QFTIR spectrometer as a detector of organic gasses, and thus represent an important milestone towards the development of such detectors in practical situations.

quant-ph↗

arXiv2023

Two statistical regimes in the transition to filamentation

We experimentally investigate fluctuations in the spectrum of ultrashort laser pulses propagating in air, close to the critical power for filamentation. Increasing the laser peak power broadens the spectrum while the beam approaches the filamentation regime. We identify two regimes for this transition: In the center of the spectrum, the output spectral intensity increases continuously. In contrast, on the edges of the spectrum the transition implies a bimodal probability distribution function for intermediate incident pulse energies, where a high-intensity mode appears and grows at the expense of the original low-intensity mode. We argue that this dual behavior prevents the definition of a univoquial threshold for filamentation, shedding a new light on the long-standing lack of explicit definition of the boundary of the filamentation regime.

physics.optics↗