Experimental study of a random fiber laser made from the combination of single-mode fiber and dispersion compensated fiber

Random lasing (RL) characteristics through different combinations of single-mode fiber (SMF) and dispersion compensated fiber (DCF) with a Raman pump (i.e., DCF is mounted at the front or at the end of the SMF; the length of the SMF and DCF is also changeable) are studied in this paper. The results indicate that the position and length ratio of DCF and SMF influence the output of the random distributed feedback fiber laser (RDF-FL) greatly (e.g., lasing threshold, spectrum stability, and shape). When the DCF is located at a position where higher laser power is distributed, RL can be enhanced remarkably. In addition, second-order RDF-FL is realized in an SMF/DCF mixed cavity pumped bidirectionally from the fiber center, indicating that the pump method is also an important factor that influences the performance of the RDF-FL. These results are useful for revealing the role of DCF in RL and light amplification, and also for providing theoretical support for flexible design and optimization of the RDF-FL.