Fig. 1. Schematic of figure-eight ring cavity laser

Fig. 2. Experimental setup of ring cavity laser

Fig. 3. Schematic of temperature control system for laser

Fig. 4. Output power of laser versus pump power

Fig. 5. Power stability of laser in 4 h. (a) Power stability of FW laser; (b) power stability of SHW laser

Fig. 6. FW laser transmission intensity obtained by Fabry-Perot interferometer

Fig. 7. Frequency fluctuation of FW laser

Fig. 8. Fine tuning FW laser by changing PZT voltage

Fig. 9. Tuning FW laser by changing Nd∶YVO₄ temperature

Fig. 10. Tuning FW laser by coordinated control of laser crystal temperature and PZT voltage

Fig. 11. Absorption spectrum lines obtained by scanning iodine molecular cell