WSe/BN heterostructure as saturable absorber for a diode-pumped passively Q-switched 2 µm solid-state laser.

We have successfully achieved the synthesis of heterojunction consisting of WSe and BN, by using a liquid phase exfoliation method, and characterization of the prepared materials under the microstructure. The WSe/BN heterojunction was used as a saturable absorber in the Tm:YAP laser for passively Q-switched operation, and a pulsed laser with an output wavelength around 2 µm range was successfully obtained. After comparing the effects of resonators composed of different cavity mirrors, it is concluded that when the curvature radius of the input mirror is 250 mm and the transmittance of the output coupler is 2.5%, the best output performance was obtained. The maximum average output power of 834 mW was achieved, with a pulsed repetition frequency of 43.51 kHz and a minimum pulse duration of 1.28 µs, corresponding to a peak power of 14.97 W and a maximum single pulse energy of 19.17 µJ.