In this letter, the polarization properties of a random fiber laser operating via Raman gain and random distributed feedback owing to Rayleigh scattering are investigated for the first time. Using polarized pump, the partially polarized generation is obtained with a generation spectrum exhibiting discrete narrow spectral features contrary to the smooth spectrum observed for the depolarized pump. The threshold, output power, degree of polarization and the state of polarization (SOP) of the lasing can be significantly influenced by the SOP of the pump. Fine narrow spectral components are also sensitive to the SOP of the pump wave. Furthermore, we found that random lasing's longitudinal power distributions are different in the case of polarized and depolarized pumping that results in considerable reduction of the generation slope efficiency for the polarized radiation. Our results indicate that polarization effects play an important role on the performance of the random fiber laser. This work improves the understanding of the physics of random lasing in fibers and makes a step forward towards the establishment of the vector model of random fiber lasers.
Bibliographical note© 2015 Astro Ltd
Funding: RC Ultralaser project, Natural Science Foundation of China (61205048, 61290312), Research Fund for the Doctoral Program of Higher Education of China (20120185120003), Fundamental Research Funds for the Central Universities (ZYGX2012J002), the PCSIRT project (IRT1218), and the 111 project (B14039).
- Raman laser
- random distributed feedback laser
- random laser