Passively Q-switched Tm:YAP laser with a zeolitic imidalate framework-67 saturable absorber operating at 3H4→3H5 transition

In the present work, we report the first Q-switching operation at similar to 2.3 mu m based on a Tm3+:YAlO3 (Tm:YAP) crystalline gain medium and a zeolitic imidazolate framework-67 (ZIF-67) saturable absorber. The ZIF-67 nanomaterials were designed and fabricated to possess a small size in the range from 200 to 500 nm in order to the reduce the possible scattering when working as the nonlinear optical modulator. Based on the conventional Z-scan technique with a home-made excitation source at 2275 nm, the modulation depth of ZIF-67 saturable absorber was determined as large as 6.9%, indicating the great potential in the short Q-switching pulse generation. With an output coupler (OC) of T = 0.5%, a maximum output power of 455 mW was achieved with a slope efficiency of 27%. For the Q-switching operation at 2.3 mu m with ZIF-67 saturable absorber, the highest output power of 220 mW and a minimum pulse duration of 220 ns were obtained with a pulse repetition rate of 95 kHz at 2271.7 nm.