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PhD : a new generation of atmospheric lidars by coherent combination of semiconductor amplifiers.

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Français - Anglais

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General information

Reference : UMR8501-PATGEO0-011
Workplace : PALAISEAU
Date of publication : Thursday, March 26, 2020
Scientific Responsible name : Gaëlle LUCAS-LECLIN
Type of Contract : PhD Student contract / Thesis offer
Contract Period : 36 months
Start date of the thesis : 1 October 2020
Proportion of work : Full time
Remuneration : 2 135,00 € gross monthly

Description of the thesis topic

Current environmental issues require advanced atmospheric monitoring in order to quantify the precise aerosol distribution, proportion of different gases, ... It is thus critical to investigate new approaches for laser sources suitable to the needs of lidars dedicated to the atmosphere analysis. Laser diodes, thanks to their electrical-optical efficiency, compactness and robustness, are an interesting candidate for that purpose. However, the optical energy extracted from single devices remains insufficient. We propose to implement a coherent combining architecture of pulsed semiconductor amplifiers and to evaluate the potential of this new configuration for lidars.

Coherent combination consists in the constructive superposition of beams from several phase-locked laser sources. This technique makes it possible to increase the laser power without degrading the other properties of laser beams, in particular their spectrum and their spatial profile. Coherent combination is of particular interest with semiconductor lasers to overcome the thermo-optical limits of individual components.

In the context of this thesis, we propose to evaluate the dynamic operation of different types of semiconductor amplifiers in pulsed mode (power, phase, spatial profile, ...). We will develop an experimental setup for the coherent combination of these components in an N-arm interferometer injected by a single laser source. We will study the performance of this module for the more specific needs of atmospheric lidars. We will also investigate the capability of the setup to be tunable over a wide spectral range. All of these results are likely to open new fields of application to semiconductor sources, for example in biomedicine or material processing.

The objective is to demonstrate the potential of coherent combination of semiconductor amplifiers for new applications, in particular lidars, by extending the operating ranges of current devices (spectrum, time domain).

The Lasers group of the Charles Fabry Laboratory (https://www.lcf.institutoptique.fr/groupes-de-recherche/lasers) has been working for several years around the coherent combination of lasers and amplifiers, in collaboration with European industrial and academic partners specialized in the design, realization and modelling of such components.

This work is being carried out in collaboration with the Laboratoire des Sciences du Climat et de l'Environnement (CEA, Saclay, https://www.lsce.ipsl.fr/).

More information on this subject :
T.Y. Fan, IEEE J. Sel. Top. Quant. Electron. 11(3), 56 (2005)
P. Albrodt et al, Optics Express 27(20), pp 27891-27901 (2019)
S. Spuler et al., Atmos. Meas. Tech., 8, 1073–1087 (2015)

Work Context

The Lasers group of the Charles Fabry Laboratory (https://www.lcf.institutoptique.fr/groupes-de-recherche/lasers) has been working for several years around the coherent combination of lasers and amplifiers, in collaboration with European industrial and academic partners specialized in the design, realization and modelling of such components.

This work is being carried out in collaboration with the Laboratoire des Sciences du Climat et de l'Environnement (CEA, Saclay, https://www.lsce.ipsl.fr/)

Funding provided by the CNRS as part of the 80Prime 2020 call for projects.

Application procedure:
Applications should include a CV, a covering letter, a letter of recommendation and all transcripts and copies of diplomas.
To be sent by Email to Gaëlle Lucas-Leclin (gaelle.lucas-leclin@institutoptique.fr)

Constraints and risks

No particular risk, implementation of laser safety procedures, possibility of in-flight experiments within the framework of the French instrumented aircraft service for environmental research (SAFIRE).

Additional Information

Offer intended for candidates holding an engineering degree in optics, a Research Master 2 with a strong focus on optics or equivalent.

The criteria sought are :
- Solid knowledge in optics, lasers
- Very high scientific rigour
- A definite taste for experimentation
- Autonomy and motivation

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