Papers by Keyword: Second-Harmonic Generation

Abstract: In the work, magnetization-induced second-harmonic generation (MSHG) effect has been appliedto investigate the magnetization distribution changes, induced by ion implantation into thethin surface layer of garnet film.The studies were performed on the (111)-orientedepitaxial garnet film (YSmLuCa)$_3$(FeGa)$_5$O$_{12}$ implanted with $1.5\times10^{16}$~cm$^{-2}$dose of H$_2^+$ ions at $60$~keV energy. The measurements of the MSHG effectwere performed as a function of amplitude of perpendicular external magnetic field. The observed complex field dependencesof the remagnetization processes for the implanted garnet film studied were described in theframe of a phenomenological model developed. The model of the MSHG effect allows to performdecomposition of measured dependences on separate contributions originating from magnetizationcomponents related to implanted and unimplanted film volumes.

Abstract: This paper demonstrates optical second-harmonic generation (SHG) and two-photon excited photoluminescence (2P-PL) imaging of 3C-SiC inclusions forming triangular and carrot-type defects in 4H-SiC epilayers. Triangular defects exhibit clear SHG images because 3C-SiC is SHG active, but not 4H-SiC host crystal in c-axis incidence. A carrot defect provides SHG and 2P-PL images in different regions in a basal-plane fault area. The spectrums of the SHG and 2P-PL are also investigated, and their emission mechanisms discussed.

Abstract: This report presents the synthesis, growth, crystal structure determination and second-harmonic generation efficiency of nonlinear optical co-crystal 4-N, N-dimethylamino-4-N-methyl-stilbazolium (m-nitrobenzenesulfonate)_0.6I_0.4 (DSIMNS)_. It is co-crystal of two DAST (4-N,N-dimethylamino-4-N-methyl-stilbazolium tosylate) derivatives. X-ray crystallographic analyses revealed that the crystal structure of DSIMNS is monoclinic, with space group P2₁. Kurtz powder test has shown that DSIMNS exhibits a large second-harmonic generation efficiency 500 times of that of urea.

Abstract: The influence of step and domain boundary on growth of Si(111)-√ 3×√3-Ag has been studied in situ using optical surface second-harmonic generation and low energy electron diffraction. The second harmonic intensity shows a difference of about 50% for Si(111) surfaces with different miscut angles and domain boundary densities, although no significant difference has been observed in low energy electron diffraction patterns, indicating a significant impediment to the growth of Si(111)-√ 3×√3-Ag by step and domain boundaries. Simulation results reveal a 90% coverage of Si(111)-√ 3×√3-Ag on the vicinal substrate with an miscut angle of 0.41o, consistent with the dynamics of Ag atoms on Si(111)-7×7 surface. The influence of two dimentional adatom gas on surface structure has also been discussed.

Abstract: The works are focused on finding out proper shape of reversed domains to obtain effective harmonic generations with high conversion efficiency. The conversion efficiency of second harmonic wave in two-dimensional nonlinear photonic crystals consisting of square lattice and reversed domains of various shapes are studied numerically. The shapes of reversed domains are extended from circle, square to ellipse and rectangle. The conversion efficiency of different order quasi-phase matched process can be maximized by adjusting the orientation of noncircular reversed domains. Moreover, a cross-shaped reversed domain is utilized to improve the conversion efficiency of two-order non-collinear quasiphase matching.

Abstract: In the framework of the vibronic theory of ferroelectricity for the transparency region of tetragonal BaTiO3 components and of nonlinear optical susceptibility responsible for the second harmonic generation and the optical rectification are calculated. Selection rules for dipole transitions in the Γ point of the first Brilouin zone are extended over the whole zone. Calculations are confined to lowest order in expansion of susceptibilities in power series of low symmetry lattice distortion. Numerical values of susceptibilities have experimentally observed order of magnitude. The spectral behavior of and is calculated as well.

Abstract: Using the first-principle DFT method, the band structure and density of state are investigated. Then using the anharmonic oscillator model, the linear and nonlinear optical properties of frequency dependence are calculated for CBOB (Cd₄BiO(BO₃)₃) crystal material. It is shown that the calculated SHG coefficient is well matched with our experimental value at a wavelength of 1064 nm, and a large nonlinear optical response originates from the charge transfers within the irregular BiO₆, CdO_n groups and BO₃ group for Cd₄BiO(BO₃)₃.

Abstract: CdS doped lead silicate glasses were prepared with the conventional fusion method. The effects of the ZnO/CdS ratio and the content of CdS on the preparation of CdS doped glasses were both studied. The crystallization process of CdS nanocrystals was investigated by X-ray diffractometry and scanning electron microscopy. Utilizing the Maker fringe method, Second harmonic generation (SHG) was observed from CdS doped glasses without any poling procedures. The SH intensity gets enhanced by increasing the heat-treatment temperature and prolonging the heat-treatment duration.

Abstract: For RbTiOPO4 (RTP) crystal, the second harmonic generation (SHG) properties of 1064nm are discussed, including phase matching (PM) direction, effective nonlinear optical coefficient (deff), walk-off angle, and angular acceptance. For the frequency doubling of nano-second and pico-second Nd:YAG laser, the conversion efficiency of RTP crystal can reach 51 % and 57 %, respectively. The laser damage threshold of RTP crystal is measured.

Abstract: We investigated the crystallization behavior of langasite-type phases in the stoichiometric corresponding glasses, i.e., Na2CaGe6O14, Na2SrGe6O14 and Pb3Ga2Ge4O14. The langasite-type phases singly were formed by heat-treatment in the glasses. Raman spectroscopy revealed the structural similarity on the scale of short-/medium-range order between the langasite-type phases and the corresponding glasses. Furthermore, we also examined the temperature dependence of second-harmonic (SH) intensity of the langasite-type phases. The SH-temperature curves exhibited an anomalous behavior, implying a structural change, e.g., isomorphous phase transition.