Random laser in a fiber: combined effects of guiding and scattering lead to a reduction of the emission threshold

Random fiber lasers incorporate scattering particles with optical gain in a fiber geometry and offer potential for sensing and biophotonics applications. In this work, the combined effects of waveguiding and scattering in random fiber lasers were investigated. A dye solution with nanoparticles was inffltrated into the hollow core of the microstructured optical fibers and the fibers were side pumped by a frequency-doubled Nd:YAG laser. The resulting emission threshold was reduced in comparison with the bulk solution. We used a Matlab model to gain a better understanding of the competing feedback mechanisms involved.