Study on the thermal and optical properties of Li+-modified Yb3+-doped Ca3Nb1.6875Ga3.1875O12 single crystal grown by the Bridgman method

Abstract

Yb³⁺-doped Ca₃Nb_1.6875Ga_3.1875O₁₂ (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 crystals grown by the Bridgman method, as well as the structural and functional alterations induced by O₂-annealing and Ar-annealing treatments. The Yb:CLNGG crystals were characterized by Raman spectroscopy, X-ray photoelectron spectroscopy, transmission spectroscopy, and 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 the Ar environment and the luminescence lifetime was extended from 1.26 ms to 1.46 ms. The above results indicate that the performance of the Yb:CLNGG crystal is improved after annealing in Ar and it is a suitable material for ultrafast lasers.