Calculations of hyper-Raman tensor components of alkali halides

Abstract

Calculations of hyper-Raman scattering by the zone-centre optical phonons in NaCl, KCl and KBr crystals based on the bond polarizability approach are presented. The results obtained for the hyper-Raman tensor components are in agreement with experimental data reported previously in literature. A weak cubic anisotropy of the hyper-Raman tensor is found. For the LO mode our results predict the lattice and electro-optic contributions to hyper-Raman scattering to be of the same order of magnitude.

<title>Calculations of third-order electronic susceptibility of alkali halides</title>

“…This proves that in the alkali halides the cubic anisotropy of the electrooptic contribution to the HR tensor is not strongly exhibited. When comparing our results with the previous experimental and theoretical results 10 '°'2 one observes that the lattice and electro-optic contribution to HR scattering are of comparable magnitudes.…”

“…When the local changes in the symmetry due to the lattice vibrations are neglected, contributions of all bonds in the unit cell cancel themselves and Xi) vanishes on the macroscopic level. 10 However, when fonons locally brake the inversion symmetry, an observation of scattering of light in the vicinity of the second harmonic of the incident light, i.e. hyper-Raman scattering, is possible.…”

<title>Effect of divergence of light wave and alignment of crystal on the response of electro-optic modulators</title>

“…MEASUREMENTS OF THE QUADRATIC ELECTROOPTIC EFFECT Studies of electrooptic properties of crystals are of interest from the point of view both applications and an understanding of the nature of relevant nonlinear susceptibilities. The latter is important because the same nonlinearities are responsible for other nonlinear optical effects (see, for example, Refs 9,[12][13][14][18][19][20][21][22][23]. Furthermore, measurements of quadratic electrooptic coefficients allow to investigate the paraelectric-ferroelectric phase transition in ferroelectric crystals.…”