LPL - Laboratoire de Physique des Lasers

Thesis position

Widely tunable ultra-stable and SI-traceable quantum cascade lasers for frequency metrology and mid-infrared precise spectroscopy: application to space, atmospheric and fundamental physics


Post: PhD student position in ultra-precise mid-infrared molecular spectroscopy
Department: Laboratoire de Physique des Lasers, CNRS-Université Sorbonne Paris Nord
Location: Villetaneuse, France
Team: Metrology, Molecules and Fundamental Tests
Supervisors: Benoît Darquié (tenured researcher), Anne Amy-Klein (professor)
Contract type: Fixed Term (36 months, starting this autumn)


Job Description
Ultra-high spectral resolution molecular spectroscopy is an interdisciplinary field with fascinating and far-reaching applications ranging from fundamental physics to astrophysics, earth sciences, remote sensing, metrology and quantum technologies. Among recent instrumental advances, the stabilization of quantum cascade lasers (QCLs) on commercial optical frequency combs with traceability to primary frequency standards, a method recently implemented in our team, is a breakthrough technology. It offers an unprecedented level of precision and resolution in the mid-infrared, an essential region known as the molecular fingerprint region, which hosts a considerable number of intense vibrational signatures of molecules of various interests. While the need for ultimate frequency control is obvious for fundamental applications such as testing fundamental symmetries or measuring fundamental constants and their possible variations, other fields such as atmospheric monitoring have surprisingly the same requirement. Molecular remote sensing measurements are often limited by the quality of spectroscopic data, resulting from the limited resolution of traditional spectrometers. The limited accuracy obtained for parameters affecting the line profile, such as frequency shifts and widths, leads to systematic biases in the determination of atmospheric species abundances, which is a crucial information for environmental and human health issues.


The techniques developed at the Laboratoire de Physique des Lasers can be used to overcome this type of bottlenecks in atmospheric sciences for example, but they still suffer from certain limitations that allow only a limited number of relatively simple species to be studied over a reduced spectral window. The successful candidate will actively participate in the development and operation of a new generation spectrometer for precise mid-infrared vibrational spectroscopy based on QCLs calibrated on some of the world's best atomic clocks. She/he will be responsible for improving the device in terms of spectral resolution, tunability, spectral coverage, detection sensitivity and flexibility. The proposed technology is at the forefront of time-frequency metrology and will be used for spectroscopy at unprecedented levels of accuracy and frequency metrology of species of various interests: from fundamental physics to astrophysics, Earth sciences and climate change research, medical diagnostics, detection of pollutants, hazardous materials or quantum technologies. An important perspective of this project is to bring increasingly complex polyatomic molecular systems within reach of precision measurement experiments.


Keywords: ultra-high resolution vibrational spectroscopy, mid-infrared, frequency metrology, Doppler-free methods, precision measurements, optical frequency comb lasers, quantum cascade lasers, molecular physics, quantum physics, optics and lasers, vacuum techniques, electronics, programming and simulation


Relevant publications: Santagata et al, Optica 6, 411 (2019); Argence et al, Nature Photon. 9, 456 (2015), arXiv:1412.2207


Requirements: The applicant should have an (almost) completed master degree in a relevant area of experimental physics or chemical physics: atomic, molecular and optical physics, spectroscopy, lasers, quantum optics. She/he will be expected to display the initiative and creativity, together with the appropriate skills and knowledge, required to meet the project goals. Only students who are nationals of the European Union, the UK or Switzerland are eligible. Interested applicants should email a CV, a brief description of research interests and the contact details of 2 referents to Benoît Darquié


See: 20200618MMTOffreTheseGb.pdf

 

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