Fig. 1. Experimental device diagram of LiNbO₃ acousto-optic Q-switched 2.79 μm Er,Cr∶YSGG laser and transmittance of LiNbO₃ crystal. (a) Experimental device diagram; (b) transmittance

Fig. 2. Thermal focal lengths under various pump powers

Fig. 3. Output energy versus pump energy for laser in free running state when repetition rate is 100 Hz

Fig. 4. Pulse energy versus pump energy under different reflectivity values

Fig. 5. Q-switched output characteristics of laser. (a) Pulse energy and pulse duration versus pump energy; (b) pulse profile at 4.36 mJ;(c) corresponding pulse train

Fig. 6. Pulse energy and pulse duration versus pump energy under different RFDPs. (a) Pulse energy; (b) pulse duration

Fig. 7. Beam quality and far-field beam profile

Fig. 8. Pulse energy fluctuation in 30 min