Experimental optimization and dynamics solution of active-passive Q-switched intracavity optical parametric oscillator based on EO modulator and layered-WSe2 SA

Abstract By applying a prepared 3 nm-thick tungsten diselenide (WSe2) saturable absorber to an electro-optic (EO) modulated fundamental-light laser, an active and passive Q-switched intra-cavity optical parametric oscillator (IOPO) has been experimentally realized. Benefiting from the saturable absorption property of WSe2, the output characteristics of Q-switched IOPO with signal-light oscillating are obviously improved, including the 93.7%-increased peak power, 54.6%-compressed pulse width, 30.1%-improved conversion efficiency, 60.1%-improved pulse-train stability, 17.8%-improved beam quality, and 27.4%-shortened linewidth. With the values of absorption parameters calculated from the measured nonlinear-transmittance curve of WSe2, the rate equations for dual-loss Q-switched IOPO with WSe2 saturable absorber and electro-optic modulator are numerically solved. The theoretical values correspond to the experimental data well.