Doubly Q-switched green thin-disk laser based on PPLN frequency doubling

To meet the demand for green pulsed lasers with short pulse durations, high peak power, and high output stability, a doubly Q-switched green thin-disk laser based on periodically poled lithium niobate (PPLN) frequency-doubling crystal was designed. The laser employed a V-shaped folded resonator structure, with an 808 nm laser diode (LD) end-pumping the thin-disk gain medium, and combined the active acousto-optic (AO) Q-switching with the passive gallium arsenide (GaAs) saturable absorption Q-switching. Green pulsed output at 532 nm was achieved through intracavity frequency doubling. Experimental results demonstrate that the double Q-switched configuration effectively compresses the pulse duration, improves the symmetry of the pulse waveform, suppresses the inherent falling-edge tailing phenomenon of AO single Q-switching, and significantly enhances the peak power. Furthermore, continuous 5-hour monitoring of the output power and central wavelength indicates excellent long-term operational stability.