The passive Q-switching Tm, Ho co-doped GAGG state laser operating near 2.1 μm

In this letter, we report on a diode pumped passive Q-switching Tm, Ho:GAGG laser at 2090.8 nm with a graphene saturable absorber mirror. In continuous wave operation, a maximum output power of 297 mW at 2114.1 nm is achieved, corresponding to a slope efficiency of 8%. In the passive Q-switching regime, stable pulses are obtained with a shortest pulse width of 576.9 ns and pulse repetition rate of 69.46 kHz. The single pulse energy is 0.3 μJ, corresponding to a pulse peak power of 0.52 W. To the best of our knowledge, this is the first report on the passive Q-switching Tm, Ho:GAGG laser.