Browsing by Author "Huang, Jung-Yau"

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Characterization of Nonlinear Optical Properties of Crystal RbGeCl(3)center dot x(H(2)O) in Infrared Region
(2009-08-01)
Tang, Li-Chuan
;
Liu, Li-Qiang
;
Chang, Yia-Chung
;
Yao, Jui-hsien
;
Huang, Jung-Yau
The nonlinear optical (NLO) property of hydrated rubidium germanium chloride (HRGC), RbGeCl(3)center dot x(H(2)O), is identified. Infrared absorbtion data support structural evidence that HRGC contain co-ordinated water molecules with strong hydrogen bond. The infrared spectrum indicated HRGC is transparent in most of the infrared region with only little influence from water. Calculations base on density functional theory shows that the band gap of the RbGeCl(3) (RGC) crystal is at least 3.84 eV, which is larger than that of the infrared (IR) NLO crystal CsGeCl(3). Single crystals of HRGC, sized up to 3 x 2 x 1cm(3), were grown in aqueous solution by a slow dehydrate technique. The synthetic, structural and optical propertiels of an off-centrosymmetric IR nonlinear optical (NLO) RbGeCl(3)center dot x(H(2)O) crystal were investigated experimentally. Powder second harmonic generation (PSHG) measurement indicated that the crystal structure of HRGC becomes off-centrosymmetric. Precise X-ray diffraction measurements showed that [100] family diffraction peaks split slightly. Unlike the RGC crystal structure whose space group is P2(1)(m) over bar, the HRGC crystal loses the inversion symmetry. Comparisons with known NLO material KH(2)PO(4) (KDP), indicate that HRGC's NLO susceptibility, x((2)), is about one third of that for KDP. The absorption edge of HRGC occured at 310 nm (approximate to 4.0ev), which indicated NLO HRGC crystal can have larger laser damage threshold. According to the Fourier transform infrared (FTIR) measurement, HRGC has a transparent region from 0.31 to 30 mu m, thus it can be applied to wider optical spectrum from ultraviolet, visible to mid-IR. (C) 2009 The Japan Society of Applied Physics
Characterization of Nonlinear Optical Properties of Crystal RbGeCl3 center dot x(H2O) in Infrared Region
(2009-08-01)
Tang, Li-Chuan
;
Liu, Li-Qiang
;
Chang, Yia-Chung
;
Yao, Jui-hsien
;
Huang, Jung-Yau
The nonlinear optical (NLO) property of hydrated rubidium germanium chloride (HRGC), RbGeCl3 center dot x(H2O), is identified. Infrared absorbtion data support structural evidence that HRGC contain co-ordinated water molecules with strong hydrogen bond. The infrared spectrum indicated HRGC is transparent in most of the infrared region with only little influence from water. Calculations base on density functional theory shows that the band gap of the RbGeCl3 (RGC) crystal is at least 3.84 eV, which is larger than that of the infrared (IR) NLO crystal CsGeCl3. Single crystals of HRGC, sized up to 3 x 2 x 1cm(3), were grown in aqueous solution by a slow dehydrate technique. The synthetic, structural and optical propertiels of an off-centrosymmetric IR nonlinear optical (NLO) RbGeCl3 center dot x(H2O) crystal were investigated experimentally. Powder second harmonic generation (PSHG) measurement indicated that the crystal structure of HRGC becomes off-centrosymmetric. Precise X-ray diffraction measurements showed that [100] family diffraction peaks split slightly. Unlike the RGC crystal structure whose space group is P2(1)(m) over bar, the HRGC crystal loses the inversion symmetry. Comparisons with known NLO material KH2PO4 (KDP), indicate that HRGC's NLO susceptibility, x((2)), is about one third of that for KDP. The absorption edge of HRGC occured at 310 nm (approximate to 4.0ev), which indicated NLO HRGC crystal can have larger laser damage threshold. According to the Fourier transform infrared (FTIR) measurement, HRGC has a transparent region from 0.31 to 30 mu m, thus it can be applied to wider optical spectrum from ultraviolet, visible to mid-IR. (C) 2009 The Japan Society of Applied Physics
First Principles Calculations of Linear and Second-Order Optical Responses in Rhombohedrally Distorted Perovskite Ternary Halides, CsGeX(3) (X = Cl, Br, and I)
(2009-11-01)
Tang, Li-Chuan
;
Chang, Yia-Chung
;
Huang, Jung-Yau
;
Lee, Ming-Hsien
;
Chang, Chen-Shiung
Systematic studies based on first-principles calculations of second. order optical susceptibilities as well as the dielectric function of CsGeX(3) (X = Cl Br, and I, CGX) are presented The relationship between structural properties and optoelectronic responses are examined The structural factors Delta alpha, and d(Ge), d(x) are proposed to describe the degree of distortion from an ideal perovskite structure. Delta alpha and dGe increase when halide anions are changed from Cl to I, while halide anion displacement, dx, decreases. The structural distortion effect on these rhombohedral CGX crystals is analyzed by first-principles calculations The dielectric function and the second harmonic generation (SHG) response coefficient also increase with increasing Delta alpha and d(Ge). The direct band gaps (E(c)) of CsGeX3 ail occur at the R-point, Delta E(R) The experimental band gaps of CGX crystals become smaller. i e, E(G)(CGI) (= 3 67eV) > E(G)(CGB) (=2 32 eV) > E(G)(CGI) (= 1 53eV), as Delta alpha and el increase, i e. d(Ge)(CGC) < d(Ge)(CGR) < d(GB)(CGI) Partial density of states (PDOS) analysis revealed that the valence band maximum (VBM) and conduction band minimum (CBM) are mainly contributed by the p-orbitals of germanium. The calculated magnitudes of chi((2))(ijk) are close to some reported experimental values near the band gap (C) 2009 The Japan Society of Applied Physics
First Principles Calculations of Linear and Second-Order Optical Responses in Rhombohedrally Distorted Perovskite Ternary Halides, CsGeX3 (X = Cl, Br, and I)
(2009-11-01)
Tang, Li-Chuan
;
Chang, Yia-Chung
;
Huang, Jung-Yau
;
Lee, Ming-Hsien
;
Chang, Chen-Shiung
Systematic studies based on first-principles calculations of second. order optical susceptibilities as well as the dielectric function of CsGeX3 (X = Cl Br, and I, CGX) are presented The relationship between structural properties and optoelectronic responses are examined The structural factors Delta alpha, and d(Ge), d(x) are proposed to describe the degree of distortion from an ideal perovskite structure. Delta alpha and dGe increase when halide anions are changed from Cl to I, while halide anion displacement, dx, decreases. The structural distortion effect on these rhombohedral CGX crystals is analyzed by first-principles calculations The dielectric function and the second harmonic generation (SHG) response coefficient also increase with increasing Delta alpha and d(Ge). The direct band gaps (E-c) of CsGeX3 ail occur at the R-point, Delta E-R The experimental band gaps of CGX crystals become smaller. i e, E-G(CGI) (= 3 67eV) > E-G(CGB) (=2 32 eV) > E-G(CGI) (= 1 53eV), as Delta alpha and el increase, i e. d(Ge)(CGC) < d(Ge)(CGR) < d(GB)(CGI) Partial density of states (PDOS) analysis revealed that the valence band maximum (VBM) and conduction band minimum (CBM) are mainly contributed by the p-orbitals of germanium. The calculated magnitudes of chi((2))(ijk) are close to some reported experimental values near the band gap (C) 2009 The Japan Society of Applied Physics