Fig. 1. Schematic of experimental setup of active Q-switching based on RBG combined with etalon

Fig. 2. Spectral profile of normalized transmittance of RBG

Fig. 3. Multi-beam interference patterns of free-running laser output using planar mirror and RBG. (a) Multiple longitudinal modes; (b) two longitudinal modes; (c) three longitudinal modes

Fig. 4. Spectrogram when central wavelength of etalon matched with that of RBG

Fig. 5. Multi-beam interference patterns of laser output using RBG and etalon. (a) Continuous-wave single-frequency output; (b) Q-switched single-frequency output

Fig. 6. Output power versus absorbed pump power

Fig. 7. Measurement of Q-switched pulse duration

Fig. 8. Simulation of longitudinal mode selection using RBG and etalon.(a)Transmission rate versus angle for etalon at 1063.9 nm; (b) transmission versus wavelength for etalon combined with RBG; (c) transmission for etalon combined with RBG and adjacent laser modes