Yb3+-doped Ca3Nb1.6875Ga3.1875O12 (Yb:CLNGG) crystals with structural disorder have widespread applications in laser fields. In this paper, we study the thermal and optical properties of Yb:CLNGG single crystal grown by the Bridgman method, as well as the structural and functional alterations induced by O2-annealing and Ar-annealing treatments. The Yb:CLNGG were characterized by Raman spectroseopy, X-ray photoelectron spectroscopy, transmission spectroscopy, emission spectroscopy. The absorption cross section, emission cross section, and gain cross section of the Yb:CLNGG were calculated. The emission bandwidth of Yb:CLNGG was enhanced from 22 nm to 29 nm by annealing in Ar environment and the luminescence lifetime was extended from 1.26 ms to 1.46 ms. The above results indicate that the performance of Yb:CLNGG crystal is improved after annealing in Ar and is a suitable material for ultrafast lasers.
