Properties of LiGa0.5In0.5Se2: A Quaternary Chalcogenide Crystal for Nonlinear Optical Applications in the Mid-IR

Abstract

LiGaSe 2 (LGSe) and LiInSe 2 (LISe) are wide band-gap nonlinear crystals transparent in the mid-IR spectral range. LiGa 0.5 In 0.5 Se 2 (LGISe) is a new mixed crystal, a solid solution in the system LGSe-LISe, which exhibits the same orthorhombic structure (mm2) as the parent compounds in the same time being more technological with regard to the growth process. In comparison withLGSe and LISe its homogeneity range is broader in the phase diagram. About 10% of the Li ions in LGISe occupy octahedral positions (octapores) with coordination number of 3. The band-gap ofLGISe is estimated to be 2.94 eV at room temperature and 3.04 eV at 80 K. The transparency at the 0-level extends from 0.47 to 13 µm.LGISe crystals exhibit luminescence in broad bands centered near 1.7 and 1.25 eV which is excited most effectively by band-to-band transition. From the measured principal refractive indices and the fitted Sellmeier equations second-harmonic generation from 1.75 to 11.8 µm (fundamental wavelength) is predicted. The nonlinear coefficients of LGISe have values between those of LGSe and LISe. 6 LGISe crystals are considered promising also for detection of thermal neutrons.

Structure and Optical Properties of the Li2In2GeSe6 Crystal

“…In the LiBC 2 family with B = In and Ga and C = S and Se with an orthorhombic structure, all members are pyroelectrics (point group mm 2), whereas tellurides (C = Te) are not pyroelectrics: they crystallize in the chalcopyrite structure of −42 m symmetry . All other known quaternary Li-containing chalcogenides such as LiGa 0.5 In 0.5 Se 2 , Li 2 Ga 2 GeS 6 , and Li 2 Ga 2 GeSe 6 are also pyroelectrics with an orthorhombic structure ( mm 2). PEL is observed commonly at low temperatures, whereas at higher temperatures, the electrical conductivity of crystals increases and PEL disappears because of charge leakage: in Li 2 In 2 GeSe 6 , this occurs at T > 200 K (Figure a).…”

A Low-Wavelength Host Absorption Edge of Cesium-Lithium Borate CsLiB-=SUB=-6-=/SUB=-O-=SUB=-10-=/SUB=-

“…In this work, unalloyed (nominally pure) single crystals of optical quality CLBO grown at the Institute of Geology and Mineralogy SB RAS (Novosibirsk) by the Chokhralsky method from stoichiometric composition under conditions of high temperature gradient up to 30 K/cm [28] were used. As a result of optimization of growing regimes, crystals without cracks, inclusions visible under tenfold magnification were obtained.…”

Growth, Structure, and Optical Properties of Nonlinear LiGa0.55In0.45Te2 Single Crystals

“…Examples of promising quaternary compounds in the application to nonlinear optics are AgGa 1−x In x Se 2 17 and Cd x Hg 1−x Ga 2 S 4 , 18 for which the NCPM mode is implemented. Among the Licontaining compounds, we have recently grown single crystals of Li 2 Ga 2 GeS 6 , 19 LiGa 0.5 In 0.5 Se 2 , 20,21 LiGaGe 2 Se 6 , 22,23 and Li 2 In 2 GeSe 6 . 24 In this paper, the growth of a single crystal of the quaternary LiGa 0.55 In 0.45 Te 2 compound of optical quality is reported.…”