Wavelength-tunable, dual-wavelength Q-switched Ho3+-doped ZBLAN fiber laser at 1.2 µm

Abstract

Wavelength-flexible Q-switched Ho3+-doped ZBLAN fiber laser at 1.2 µm is experimentally investigated for the first time. The gain medium is Ho3+-doped ZBLAN fiber, which is pumped by a 1137-nm Raman fiber laser. Nonlinear polarization rotation technique works as the saturable absorber in the ring cavity to provide the intensity modulation. An artificial Lyot filter is inserted into the cavity and its periodic transmission spectrum varied with the polarization allows for the tunability and multi-wavelength operation of the laser. As a result, the laser spectrum tunable from 1190 to 1196 nm and dual-wavelength Q-switched pulses are observed. At a pump power of 2.01 W, stable Q-switched pulse train with the pulse duration of 0.76 µs and pulse energy of 0.62 µJ is achieved.