Intra-Cavity Raman Laser Operating at 1193 nm Based on Graded-Index Fiber

Nonlinear Raman frequency conversion is an important technical scheme to obtain special optical band lasers based on conventional ion-doped lasers. In our work, we designed an intra-cavity Raman fiber laser based on graded index fiber (GRIF) as the Raman gain medium. Based on the fundamental-frequency 1080-nanometer laser, efficient first-order and second-order Stokes Raman lasers were obtained, respectively. When the power of the fundamental-frequency 1080-nanometer laser was 33.4 W, the output power of the second-order 1193-nanometer laser was 11.39 W. The corresponding conversion efficiency was 34.1%. To our knowledge, this is the first report of a second-order Raman output based on a GRIF and intra-cavity structure. In the experiment, the spectrum-purification process with the increase in power was also observed. Our experimental results prove that the intracavity Raman-laser system based on graded index fiber with a high optical conversion efficiency has important application potential for obtaining new special-application bands.