Fig. 1. Experimental setup of LD-pumped 1064 nm single-longitudinal-mode passively Q-switched laser

Fig. 2. Q-switched pulse waveform of unidirectional ring cavity with 54 cm cavity length (illustration shows enlarged waveform at 70-80 ns)

Fig. 3. Fourier transforms of output waveforms under different cavity lengths. (a) 54 cm; (b) 84 cm

Fig. 4. Q-switched pulse waveform and its Fourier transform when etalon is inserted into ring cavity. (a) Output pulse waveform; (b) Fourier transform of waveform

Fig. 5. Output parameters of laser. (a) Output linewidth of laser; (b) energy stability of laser; (c) measurement result of M² (illustration is spot near focal point)