Crystal Growth, Characterization, and Properties of Nonlinear Optical Crystals of LixAg1- xGaSe2 for Mid-Infrared Applications

Jing Peng; Xinyao Liu; Jie Wang; Shaoqing Zhang; Xiao Xiao; Zhengbin Xiong; Kuibao Zhang; Baojun Chen; Zhiyu He; Wei Huang

doi:10.1021/acs.inorgchem.3c01582

Crystal Growth, Characterization, and Properties of Nonlinear Optical Crystals of Li_xAg_{1- x}GaSe₂ for Mid-Infrared Applications

Inorg Chem. 2023 Jul 31;62(30):12067-12078. doi: 10.1021/acs.inorgchem.3c01582. Epub 2023 Jul 21.

Authors

Jing Peng¹, Xinyao Liu¹, Jie Wang¹, Shaoqing Zhang¹, Xiao Xiao¹, Zhengbin Xiong¹, Kuibao Zhang², Baojun Chen¹, Zhiyu He¹, Wei Huang

Affiliations

¹ College of Materials Science and Engineering, Sichuan University, Chengdu 610064, China.
² State Key Laboratory of Environmentally Friendly Energy Materials, Southwest University of Science and Technology, Mianyang 621010, China.

PMID: 37475677
DOI: 10.1021/acs.inorgchem.3c01582

Abstract

Li_xAg_1-xGaSe₂ is a new series of solid solution crystals that has a large nonlinear optical (NLO) coefficient and laser-induced damage threshold (LIDT). It has great application prospects in mid-infrared laser frequency conversion. In this work, Li_xAg_1-xGaSe₂ (x = 0, 0.2, 0.4, 0.5, 0.6, 0.8, and 1) crystals (Φ 16 mm × 40 mm) were grown by the improved Bridgeman method in a four-zone furnace. It is found that the Li_xAg_1-xGaSe₂ (x = 0.2-0.8) crystals keep the same tetragonal symmetry with AgGaSe₂ and the melting and solidification temperature increase with the Li content. Because the as-grown crystals are almost opaque in the visible-NIR range, an annealing experiment is necessary. After annealing, the transmittance is improved significantly, which can meet the application requirements. The band gap is changed by annealing atmosphere; for instance, the band gap of Li_0.6Ag_0.4GaSe₂ annealed in a LiGaSe₂ powder atmosphere increases from 2.35 to 2.56 eV, while the band gap of LiGaSe₂ annealed in vacuum decreases from 3.39 to 3.01 eV. Finally, the Li_xAg_1-xGaSe₂ shows an extreme SHG response, especially Li_0.8Ag_0.2GaSe₂, which has about five times that of LiGaSe₂, proving the promising NLO properties.