Bipolarized Raman amplification for lidar transmitter.

Abstract

A comparison is made of the spectral distortions of the output radiation of a Raman amplifier in the case of one and two-polarization amplification of modulated radiation in an extended optical fiber. With an output power of 3.5 W at a wavelength of 1649 nm, the spectral distortions for bipolarization amplification are lower, which makes it possible to increase the amplifier output power to ~ 4 W, and the level of spectral distortions at the amplifier output makes possible to carry out lidar measurements of methane concentration by a remote method with high accuracy. Simulation of bipolarization Raman amplification was carried out along with experimental verification. For this simulation, the coefficient of depolarization of radiation propagating in an extended single-mode fiber was introduced. The experimental results and the results of theoretical modeling are in good agreement. An increase in the amplifier power also makes it possible to increase the methane sensing range in an open atmosphere with lidars using Raman amplifiers as transmitters.