Two-micron thulium-doped fiber lasers achieve 10 kW peak power

摘要

Highly thulium-doped silicate glass fibers can be used to develop single-frequency fiber lasers with 1.9-2.1 μm operating wavelengths, and Q-switched fiber lasers and self-starting passively modelocked fiber lasers of up to 10 kW peak power. The slope efficiency of a thulium (Tm) doped fiber laser can exceed the Stokes limit, enabling a quantum efficiency near 200% for the ~3F_4→~3H_6 transition because of the so-called cross-relaxation energy transfer between Tm ions. Using our highly Tm~(3+)-doped (3-7 wt%) silicate glass fibers fabricated by the rod-in-tube technique, laser gain fibers with high slope efficiency of 68.2% and a gain per unit length of >2 dB/cm have allowed us to demonstrate Q-switched fiber lasers and modelocked fiber lasers operating from 1.9-2.1 μm wavelengths based on Tmdoped silicate fibers with peak power levels up to 10 kW.