Polarization dynamics of ultra-narrow modes generated in random fiber lasers

Abstract

We present study of polarization properties of the narrow modes, generated in random Raman fiber lasers near the generation threshold. For this purpose, time and polarization resolved spectral measurements based on optical heterodyning technique were implemented, that allow reconstruction of the ratio of vertical and horizontal projections of the electrical field during the mode generation process. We revealed that modes have high degree of polarization, with the slow change of its state during the mode lifetime. Moreover, it appeared that each mode has its own randomly appeared state of polarization, even when the several modes are generated simultaneously.