U4+:SrF2 Efficient Saturable Absorber Q-Switch for the 1.54 μm Er: Glass Laser

Saturable absorber Q-switching of the 1.54 μm Er:glass laser using U4+:SrF2 has been obtained for the first time. Q-switched pulses of 3 mJ, 60 nanoseconds FWHM were achieved using a 2.69 mm thick Q-switch in a 14 cm long flat-flat cavity, with a 3 x 50 mm Kigre QE-7S Englass rod. Pulses of 40 mJ, 64 nanoseconds have been obtained using a 4 x 76 mm Er:glass laser rod. The high absorption cross-section of U4+:SrF2 at 1.54 μm resulted in efficient Q-switched operation (without intracavity focussing) in agreement with the theoretical predictions.