High‐Energy Pulse Generation in a Passively Q‐Switched 2 μm Laser Based on a HfSe 2 /WSe 2 Heterojunction Saturable Absorber

In this work, a HfSe 2 /WSe 2 heterojunction saturable absorber prepared by liquid‐phase exfoliation combined with spin coating was employed in a passively Q‐switched Tm:YAP laser. At an incident pump power of 17.8 W, the maximum single‐pulse energy of 34.9 μJ, repetition rate of 73.1 kHz, pulse duration of 710.5 ns, and peak power of 49.1 W were obtained. The experimental results demonstrate that the HfSe 2 /WSe 2 heterostructure exhibits excellent nonlinear modulation capability in passively Q‐switched lasers operating at 2 μm.