Gyrolaser semi-conducteur à cavité externe

TL;DR: In this paper, a ring laser gyroscope based on a semi-conductor gain medium in a free space cavity is proposed. But the performance of the system is limited by the long fluorescence time of the gain medium.

Abstract: A well known technique for gyrometry is to use Sagnac effect in a ring laser cavity, with a mixture of Helium and Neon as gain medium. Gyrometric qualities of this type of laser has been shown many times. But on an industrial point of view, the fact that the gain medium is a gas is the source of the limitations of the system. Other solutions based on Nd :YAG cristal have shown that it is possible to get a Sagnac signal in other kind of gain medium. However, the quality of the frequency response is limited by the long fluorescence time (230 μs) of this gain medium. Semi-conductor gain medium, through its much shorter luminescence time (3 ns) offers great opportunity of gyrometry. The possibility of electrical pumping could also give a string cost reduction. The goal in this thesis is to study the possibility of a ring laser gyroscope based on a semi-conductor gain medium in a free space cavity. The gain medium dynamic is strongly different from previously quote gain media. First we will have to study stability conditions of gyrometric behavior of such a system, and also gyrometric performance one can expect. Influence of phase-amplitude coupling, specific to semiconductor, will be shown. Second, experiment shows that we have been able to get a gyrometric behavior in ring cavity with a 1/2-VCSEL thanks to a suitable laser cavity geometry and a feed back loop to control laser intensities in order to counteract mode competition which take place in semiconductor gain medium.