Growth and Characterization of BaGa₄S₇: A New Crystal for Mid-IR Nonlinear Optics

Abstract

The new nonlinear optical (NLO) crystal BaGa4S7 for the mid-infrared (IR) has been grown by a Bridgman-Stockbarger technique. Polycrystalline materials with stoichiometric composition were synthesized from BaS, Ga, and S as the initial materials by solid-state reactions. The ultraviolet (UV) and IR transmittance of the crystal was determined with polished crystal pieces. The UV and IR optical absorption edges were found to be at 350 nm and 13.7 μm, respectively. From optical measurements of second harmonic generation on powders, the NLO coefficient d 33 was determined to be 12.6 pm/V. The laser damage threshold of a single crystal reached about 1.2 J/cm2 at 1.064 μm. The Vickers-hardness value of the crystal is 327.5 HV5, which is equivalent to Mohs’ hardness of about 5.

Syntheses and characterization of two new selenides Ba5Al2Se8 and Ba5Ga2Se8

“…Recently, two new infrared nonlinear optical materials, namely BaGa 4 S 7 and BaGa 4 Se 7 , have been discovered in the A/M/Q system by Lin et al [36] and our group [37], respectively. BaGa 4 Se 7 and BaGa 4 S 7 crystallize in different structure types (space groups: Pmn2 1 vs. Pc) [36][37][38], although they possess the same composition, which demonstrates the influence of cation/anion size ratio on crystal structures.…”

“…BaGa 4 Se 7 and BaGa 4 S 7 crystallize in different structure types (space groups: Pmn2 1 vs. Pc) [36][37][38], although they possess the same composition, which demonstrates the influence of cation/anion size ratio on crystal structures. Here, we report the successful syntheses of two new compounds Ba 5 Al 2 Se 8 and Ba 5 Ga 2 Se 8 as a result of our continuing exploratory investigation in the A/M/Q system.…”

Core level photoelectron spectroscopy of LiGaS2 and Ga–S bonding in complex sulfides

“…Within the past few years many binary and ternary sulfide systems were evaluated in searching for new compounds with noncentrosymmetric crystal structure and nonlinear optical (NLO) properties [2][3][4][5][6][7][8][9][10][11][12]. Among known crystals several binary and ternary thiogallates are showing high level of NLO susceptibility and pronounced ability for solid solution formation necessary for accurate tuning of optical properties by doping [1][2][3]5,7,[13][14][15][16][17]. In all presently known NLO thiogallates the gallium atoms are coordinated by four sulfur atoms and the presence of GaS 4 groups in crystal lattice seems to be a meaningful factor for NLO properties.…”

Research progress on mid-IR nonlinear optical crystals with high laser damage threshold in China

“…From the measurements, the band-gap energy of BaGa 4 S 7 crystal is about 3.54 eV. In comparison to AgGaS 2 (2.64 eV) and ZnGeP 2 (1.75 eV), BaGa 4 S 7 crystal has a relatively large band-gap energy, and the LDT of the BaGa 4 S 7 single crystal reached about 1.2 J/cm 2 (0.12 GW/cm 2 ) at 1.064 μm (Table 1) [11].…”

“…Due to the important applications of the mid-IR NLO crystals in optical communications, IR spectroscopy, and high-energy laser system, the research to find new NLO materials with high damage resistance to the incident laser beam together with relatively large NLO coefficient, wide transparent range in the mid-IR region, and good stability to the environment has become an urgent and challenging task in the field and thus has attracted great attention worldwide. Some good progress has been achieved in the last decade or so, for which the Chinese scientists have made a considerable contribution in both aspects: improving the crystal growth technique and exploring new strategy to search for new mid-IR NLO crystals [10][11][12][13][14][15][16][17][18][19]. This paper summarizes the recent research progress in China for mid-IR NLO crystals with high LDT.…”