Growth and characterization of BaGa4Se7 crystal

Abstract High-quality crystals of BaGa 4 Se 7 , a newly developed IR nonlinear optical (NLO) material, were obtained via the Bridgman–Stockbarger technique. The FWHM of the (002) peak rocking curve is about 0.008° and the transmittance through a polished 2 mm thick (001) plate is around 65% over the wide range of 1–14 μm. Various thermophysical properties were measured on crystals. The thermal expansion behavior in BaGa 4 Se 7 does not exhibit strong anisotropy with α a =9.24×10 −6  K −1 , α b =10.76×10 −6  K −1 , and α c =11.70×10 −6  K −1 along the three crystallographic axes. The thermal diffusivity / thermal conductivity coefficients measured at 298 K are 0.50(2) mm 2  s −1 /0.74(3) W m −1  K −1 , 0.42(3) mm 2  s −1 /0.64(4) W m −1  K −1 , 0.38(2) mm 2  s −1 /0.56(4) W m −1  K −1 , along the a , b , c crystallographic axis respectively. In addition, the surface laser damage threshold was measured to be 557 MW/cm 2 using a Nd:YAG (1.064 μm) laser under conditions of 5 ns pulse width, 1 Hz frequency, and D =0.4 mm spot size.