CsPbCl3/FAPbCl3 heterojunction as a saturable absorber for passively Q-switched Tm:YAP laser

All-inorganic CsPbCl 3 , organic–inorganic hybrid FAPbCl 3 , and their heterojunction are investigated as saturable absorbers (SAs) for passively Q-switched (PQS) Tm:YAP solid-state lasers. A systematic evaluation in the 2 μm spectral region demonstrates that the CsPbCl 3 /FAPbCl 3 heterojunction possesses superior nonlinear optical properties compared to the single-component materials. Operating under 9.94 W of absorbed pump power, the laser yielded a maximum average output power of 1.93 W and a slope efficiency of 23.42%. Notably, a minimum pulse width of 602.33 ns was obtained at a repetition rate of 153.21 kHz, corresponding to a pulse energy of 12.6 μJ, a peak power of 20.9 W. These findings underscore the potential of the CsPbCl 3 /FAPbCl 3 heterojunction as a high-performance SA for 2 μm passive Q-switching.