Performance improvement of dual-GSA-wavelength pumped heavily-doped 3 μm Er:YSGG laser by using wing-pumping method

Abstract

The dual-GSA-wavelength pumping combined with wing-pumping method has been successfully used to improve the output performance of a 30 at.% Er:YSGG laser at 3 μm. According to the GSA spectrum of 4I15/2→4I9/2 transition at 0.8 μm, two pump wavelengths of 785 and 798 nm are used to verify the effectiveness of dual-GSA-wavelength pumping, with 798 nm overlapping an absorption peak, while 785 nm deviating from the absorption peak of Er:YSGG crystal. With regard to the 798/976 nm dual-wavelength pumping, the output power fails to maintain a continuous growth trend with the dual-wavelength pump power in comparison with the single-wavelength pumping at 976 nm. This indicates the influence of thermal effects on the heavily erbium-doped material is more severe, resulting in a significant reduction in the available pump power range. When the 785 nm with weak absorption is used for dual-wavelength pumping, the output power achieves a nearly linear increase within a larger range of dual-wavelength pump power. The achievable maximum output power is 662 mW for the 785/976 nm dual-wavelength pumping, respectively increased by 13.2 % and 64.7 % compared to the achievable maximum output power obtained in 976 nm single-wavelength and 798/976 nm dual-wavelength pumping. It is also found that the introduction of 785 nm pump light would lower the threshold for achieving dual-wavelength laser output for the Er:YSGG laser. The dual-GSA-wavelength pumping combined with wing-pumping method provide an effective solution for improving the performance of heavily erbium-doped lasers at 3 μm.