Power optimization of high-power random Raman laser with a full-open cavity

Since the concept of distributed feedback fiber random laser was put forward, random Raman fiber laser (RRFL) has made great progress in high power operation. For RRFL with a full-open cavity, the simplest cavity structure, further power scaling was restricted by the rapid increase of high-order Stokes wave. In this paper, we demonstrate that the output power of the RRFL can be further improved by optimizing the fiber length. The relationship between the RRFL output power and fiber length is researched theoretically and experimentally. Results show that to optimize the RRFL with a full-open cavity in output power to the best, the fiber length should be as short as possible, under the premise of avoiding causing strong four-wave mixing (FWM) and ensuring the sufficient absorption of signal light.