Investigation of laser-diode end-pumped Er:YSGG/YSGG composite crystal lasers at 2.79 μm

Abstract

The advantages of laser-diode end-pumped Er:YSGG/YSGG composite crystals in reducing thermal effects and improving output power are investigated theoretically and experimentally. Compared with Er:YSGG, the temperature rise and total additional optical path difference of Er:YSGG/YSGG are evidently reduced because of the thermal conduction effects of the undoped YSGG crystal. The maximum continuous-wave output power of 504 mW with slope efficiency of 11.2%, and 900 mW with slope efficiency of 12.1%, at 2.79 μm is obtained in a 970 nm laser-diode end-pumped Er:YSGG crystal and Er:YSGG/YSGG crystal, respectively. To our knowledge, the output power of the Er:YSGG/YSGG crystal is the highest value for a laser-diode end-pumped Er:YSGG crystal. The thermal focal length of Er:YSGG and Er:YSGG/YSGG is respectively 36 and 51.8 mm when the pump power is 5.94 W. Investigations demonstrate that the Er:YSGG/YSGG composite crystal has great advantages in reducing the influence of thermal effects and improving output power.