Electric four-wave mixing

Table 1 Coefficients for 7[ (a ) for third harmonic generation (THG), degenerate four wave mixing (DFWM), electric field induced second harmonic generation (ESHG), and Kerr effect in methane at the experimental geometry rcH = 2.052 a.u. A CCSD wavefunction and the t-aug-cc-pVDZ basis were used. (Results given in atomic units, the number in parentheses indicate powers of ten.)...

Absorption spectroscopy, quartz crystal microbalance and electrical measurements and femtosecond degenerate four-wave mixing studies of third-order optical non-linearity... 

Third-Order NLO Techniques. There is a wider range of third-order techniques commonly used to characterize materials, including electric field induced second harmonic generation (EFISH) (15, 16), third harmonic generation (THG) (17) and degenerate four wave mixing (DFWM) (18). EFISH and DFWM will be discussed briefly then... 

Poly(3-alkyl-a-thiophene) systems show significant third-order nonlinear susceptibilities ( ) Though, oligothiophenes have been studied for their third-order susceptibilities, accurate third-order optical nonlinearity data obtained by degenerate four-wave mixing or electric-field-induced second harmonic generation (EFISH) are difficult to attain reliably on samples with poor solubility characteristics (92MM1901). 

Under the influence of an optical pump, the molecular angular distribution described by Equation 12.4 can be considerably modified. In turn, this results in modification of the X/ kl tensor components. Further, we discuss the influence of a polarized pump beam on third-order nonlinear phenomena such as third harmonic generation (TFIG) [(described by XyfCL (-3a ,o ,w, u) coefficient], electric field induced second harmonic generation (EFISH) i 2co, (o, (o, 0)] and degenerate four-wave mixing (DFWM) X/yx/ -... 

The four-wave mixing technique serves to measure the diffraction efficiency t] during the writing process as a function of time and as a function of the strength of the external electric field. Figure 4.4 shows a schematic representation of a typical set-up employed in four-wave mixing experiments. 

Fig. 4.4 Schematic depiction of a set-up for a four-wave mixing experiment, as employed to measure diffraction efficiency as a function of the strength of an external electric field. Reading beam counterpropa-gating with writing beam (1). Diffracted beam counterpropagating with writing beam (2). Adapted from Kippelen et al.

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