High-pressure synthesis, growth and characterization of large-size BaGa4Se7 crystals

Abstract

BaGa4Se7 (BGSe), as a promising new infrared nonlinear optical (IR NLO) crystal, has been widely studied in recent years due to its outstanding overall properties and IR laser output performance. In this paper, the synthesis method of polycrystalline sample and the temperature field used in crystal growth of BGSe were improved. More than 200 g BGSe polycrystalline sample can be synthesized by high pressure synthesis in just 2 days. The crystal growth temperature field can be designed with the use of COMSOL MultiphysicsTM simulation software, and the experimental results fit well with the simulation results. A high-quality crystal with dimensions up to Φ40 mm × 180 mm was grown successfully by the Bridgman-Stockbarger method. The surface laser damage threshold was measured to be 7.075 J/cm2 (peak on-axial fluence) using a 1.064 μm laser under conditions of 5 ns pulse width, 1 Hz frequency, and 0.12 mm spot size. The absorption coefficient was 0.017 cm−1@4 μm for an uncoated sample.