Kerr susceptibility

The third-order optical Kerr susceptibility of nanocomposites, Xeff. formed by a non-absorbing matrix, with dielectric constant containing metal nanoclusters with low volume fraction p (i.e., filling factor) is given [95] by ... 

Many of the different susceptibilities in Equations (2.165)-(2.167) correspond to important experiments in linear and nonlinear optics. x<(>> describes a possible zero-order (permanent) polarization of the medium j(1)(0 0) is the first-order static susceptibility which is related to the permittivity at zero frequency, e(0), while ft> o>) is the linear optical susceptibility related to the refractive index n" at frequency to. Turning to nonlinear effects, the Pockels susceptibility j(2)(- to, 0) and the Kerr susceptibility X(3 —to to, 0,0) describe the change of the refractive index induced by an externally applied static field. The susceptibility j(2)(—2to to, to) describes frequency doubling usually called second harmonic generation (SHG) and j(3)(-2 to, to, 0) describes the influence of an external field on the SHG process which is of great importance for the characterization of second-order NLO properties in solution in electric field second harmonic generation (EFISHG). 

The Cartesian indices refer to an arbitrarily chosen laboratory frame. For certain NLO processes intrinsic permutation symmetry can be used to reduce further the number of independent components. In the case of the Kerr susceptibility, (-w w,0,0), intrinsic permutation symmetry in the last two indices holds, xltJ zx X xx- The most general Kerr susceptibility of an isotropic medium therefore has only two independent components, x9 zz and x9 xx Likewise, the EFISHG susceptibility (-2w w, w,0), important for the evaluation of second-order molecular polarizabilities in solution (see pp. 158 and 162), has only two independent components, x zz and x9]txz, because of intrinsic permutation symmetry in the second and third indices. 

The quadratic effect of an externally applied field on the refractive index n is described by the third-order susceptibility (- ) w,0,0) (Kerr susceptibility). The two independent components Yilzz and x ixx can be interpreted in terms of molar polarizabilities. The results for 2 symmetric molecules with only one significant component of the second-order polarizability are expressed in (113) and (114),... 

The Cartesian indices refer to an arbitrarily chosen laboratory frame. For certain NLO processes intrinsic permutation symmetry can be used to reduce further the number of independent components. In the case of the Kerr susceptibility, w,0,0), intrinsic permutation symmetry in the last two... 

Kerr susceptibility x ( ) is calculated to be larger by several orders of... 

This formula was obtained in (6) by a different method. In the mentioned paper the averaging of nonlinear equations with optical nonlinearity f°r superlattices was also performed. The predicted enhancement of the Kerr susceptibility was confirmed experimentally (7). 

X H—(o ft), 0, 0) Change of the refraction index induced by an external static field (Kerr susceptibility)... 

The part of refractive index describing its variation with light intensity n2 is directly related to the Kerr susceptibility through following equation... 

KAJZAR F., ROTHBERG L., ETEMAD S., CHOLLET P.A., GREC D., BOUDET A. and JEDJUT., (1988a), Saturation Absorption and Kerr Susceptibility in Polydiacetylene Langmuir-Blodgett Film" Opt. Commun., 66, 55-58. 

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