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Use of electro-optical frequency shifting loops for the realization of a coherent pulse compression lidar

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Date : from 1st October 2021 - Funding acquired (ANR)

Project context :

This thesis work is part of the ANR COCOA project (Coherent Lidar with all-optical analog pulse compression). This project brings together two academic partners : the LIPhy (Interdisciplinary Physics Laboratory) in Saint Martin d’Hères, and the FOTON Institute (Optical Functions for Information Technologies) in Rennes. A major industrialist in the photonics sector, Lumibird, has also lent its support to the project.

Description of the subject :

The objective of the COCOA project is to develop new architectures for coherent all-optical pulse compression lidar. Such architectures can be described as optimal. They combine numerous advantages, both in terms of performance (long range thanks to the use of quasi-continuous signals, sub-centimetric resolution governed by the spectral width of the signals, possibility of phase or velocity measurements, high signal-to-noise ratio thanks to pulse compression), simplicity (operation at 1550 nm, no fast electronics, no wide-band laser source), and flexibility. One of the envisaged architectures, which will be developed at LIPhy, is a double frequency shifting loop using electro-optical frequency shifters (or single sideband Mach Zehnder modulators). The application of this system to telemetry should make it possible to obtain very easily adjustable spatial resolutions, from the cm to the hundred µm range.

This thesis will also highlight new applications of frequency shifting loops for metrology or information processing.

Key words :

Telemetry, Coherent Lidar, Frequency combs, Multi-heterodyne interferometry (dual-comb), Pulse compression, Matched filtering, Hilbert transform.

Thesis work and required skills :

The thesis work is primarily experimental. It consists in realizing and characterizing a dual fiber loop with electro-optical frequency shift, then optimizing it in order to realize a demonstration of Lidar telemetry. The thesis also includes a more theoretical component (modelling and numerical simulations) aimed at understanding the fundamental limits of the system (resolution, SNR, dynamic range, etc.). Finally, an interface will be developed on a Labview platform to control, process and format the telemetry measurements. We are therefore looking for a candidate (M/F) with solid skills in optics. Skills in signal processing, electronics, computing and telecommunications will also be appreciated.

Contact :

Hugues Guillet de Chatellus, LIPhy ( - 0476514341