Mo:BiVO4 nanoparticles were employed as an optical modulator in a Q-switched all-solid-state Tm:YAP laser for the first time. The nonlinear optical parameters of Mo:BiVO4 nanoparticles in the 2-μm region were characterized by measuring nonlinear transmission. Saturation intensity was 718 MW/cm2, and the modulation depth was 12.3%. A stable pulse sequence was acquired with a 70.08 kHz maximum repetition rate and an 821 ns pulse width. The maximum output average power was 153 mW, corresponding to 2.18 μJ single pulse energy and 2.67 W peak power. Although the response wavelength of Mo:BiVO4 is in visible light region, our experimental results demonstrates that a saturable absorption effect for wavelengths much longer than visible light (2 μm wavelength) is still possible due to sub-bandgap absorption. Therefore, we experimentally proved that Mo:BiVO4 nanoparticles are a great candidate for use as an optical modulator of a 2-μm pulsed laser.
Keywords: nanoparticles; optical modulator; pulsed laser; saturable absorber.