Optical Second-harmonic Generation Effect Research Articles

First and second order in magnetization effects in optical second-harmonic generation from a trilayer magnetic structure

Linear and nonlinear optical properties of a thin planar CoFe/Al2O3/CoFe structure for different angles of incidence of the fundamental radiation are studied by means of the magneto-optical Kerr effect and magnetization-induced second-harmonic generation (SHG). The composition of this multilayered structure supports the appearance of the antiferromagnetic state, which leads to nonreciprocal optical effects and is discussed in terms of the magnetic toroid moment. We show that in accordance with the phenomenological description, SHG magnetic hysteresis loops for a linearly polarized pump beam are determined by linear in magnetization M components of the SHG polarization, while for a circularly polarized pump such a description necessarily involves both linear and quadratic in M components of the nonlinear polarization. Symmetry analysis of the magnetization-induced SHG supports the differences between the cases of linear and circular polarization of the incident radiation observed in the experiment, as well as a partial suppression of first in magnetization SHG contributions. Relative values of the linear and quadratic in magnetization components of the SHG polarization are estimated for the trilayer structure and for a reference homogeneous ferromagnetic film.

Magneto- and electroinduced effects in optical second-harmonic generation from a planar Au/Co/Si nanostructure

Optical second-harmonic (SH) generation in planar Au/Co/Si(111) nanostructures under application of static magnetic and electric fields is studied experimentally. The crystallographic, magneto- and electroinduced contributions to the SH intensity reveal strong azimuthal anisotropy peculiar to the Si(111) surface. The transient times characterizing the electroinduced quadratic response are found to exceed 1 s. Relative amplitudes and phases of the magneto- and electroinduced constituents of the SH signal are estimated from the measurements data.

Crystal growth and characterization of a novel inorganic–organic hybrid NLO crystal: (NH4)[Cd(NCS)3]·C12H24O6

It is reported here, for the first time, that high-quality bulk size (18 × 5 × 4 mm3) single crystals of a new nonlinear optical crystal, [(NH4)[Cd(NCS)3]·C12H24O6] [Ammonium (18-crown-6-ether) Cadmium(II) tri-thiocyanate; ACCTC], have been grown from aqueous solution via slow evaporation technique. Solubility of ACCTC has been determined for various temperatures. The grown crystals were characterized by single crystal X-ray diffraction, FT-IR, FT-Raman, and UV–Vis–NIR studies. ACCTC crystallizes in orthorhombic system with cell parameters a = 14.7568 Ǻ, b = 15.4378 Ǻ, and c = 10.6383 Ǻ with space group Cmc21. The optical second-harmonic generation effect has been measured by using the Kurtz powder technique and is found to be 2 times higher than that of KDP (KH2PO4). The sample possesses wide optical transparency range from 200 to 2,500 nm. The TG-DSC thermal analysis revealed that the sample is thermally stable up to 237.92 °C, which is comparatively far better than the thermal stability of [(18C6)Li][Cd(SCN)3]; CLTC (170 °C).

Crystal Growth, Optical Properties Measurement, and Theoretical Calculation of BPO4

Optically perfect single crystals of BPO4 (BPO) have been grown by the top-seeding flux method. The refractive indices are measured with the prism minimum-deviation method for the first time, on the basis of which the Sellmeier equation is obtained. The measured powder nonlinear optical second-harmonic generation effect is about twice that of KH2PO4 (KDP). Electronic structure, the linear refractive indices, and second-harmonic generation (SHG) coefficients of BPO are calculated on the basis of the plane-wave pseudopotential ab initio method. The calculation values are in line with the experimental data. The crystal is nonhygroscopic, chemically stable, and has a hardness of 6.5 Mohs.

Growth, Structure, and Properties of Single Crystals of SrBPO5.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Growth, Structure, and Properties of Single Crystals of SrBPO5

Single crystals of strontium borophosphate, SrBPO5, have been grown with sizes up to 25 × 15 × 10 mm3 from the BPO4 flux by the top-seeded solution growth method. The compound crystallizes in the trigonal system, space group P3221 (No. 154), with a = 6.8850(10) A, c = 6.8700(14) A, and three formula units per cell. The SrBPO5 compound is built up of infinite anionic units of BO4 and PO4 tetrahedra joined by common vertexes. It contains single chains of BO4 tetrahedra running parallel to [001], which are linked to terminal PO4 tetrahedra to form spiral chains. The ultraviolet transmission spectrum of SrBPO5 crystals was reported. The refractive indices were measured by the minimum deviation technique and fitted to the Sellmeier equations. The crystal exhibits an optical second-harmonic generation effect similar to that of KDP (KH2PO4).

A New Lanthanum and Calcium Borate La2CaB10O19

A new lanthanum calcium borate with the composition La2CaB10O19 has been synthesized. Single crystals have been grown from a melt close to the stoichiometric composition. The compound crystallizes in the monoclinic system, space group C2, with a = 11.043(3) A, b = 6.563(2) A, c = 9.129(2) A, α = γ = 90°, β = 91.47°, and two formula units per cell. The crystal structure contains B5O12 double-ring pentaborate groups, which are linked together to form an infinite two-dimensional double layer. The layer runs almost perpendicular to the c axis of the crystal. The La atoms are located in layers, while the Ca atoms are located between two layers. La2CaB10O19 exhibits an optical second-harmonic generation effect about twice as large as that of KDP (KH2PO4).

Electroinduced and photoinduced effects in optical second-harmonic generation and hyper-Rayleigh scattering from thin films of bacteriorhodopsin

The mechanism of optical second-harmonic generation (SHG) in thin solid oriented and nonoriented films of bacteriorhodopsin (bR) is studied. The role of the random spatial inhomogeneity of the quadratic susceptibility in the mechanism of diffuse and depolarized SHG in thin solid bR films is discussed. A hyper-Rayleigh scattering formalism is used for the description of SHG in these films. Electroinduced and photoinduced effects in SHG are detected, and the saturated concentrations of the electroinduced and the photoinduced spectral forms of this type of bR film are estimated. Nondestructive SHG readout of bR-based optical memories is suggested.

Size effects in optical second-harmonic generation by metallic nanocrystals and semiconductor quantum dots: The role of quantum chaotic dynamics.

Second-harmonic generation in small metallic nanocrystals and semiconductor quantum dots is studied both experimentally and theoretically. The enhancement of the nonlinear optical response with the decrease of the particle radius from 100 to about 10 \AA{} has been experimentally observed. The theoretical description based on the model of chaotic motion of noninteracting electrons in the particles agrees satisfactorily with the experimental data.