Third harmonic generation length

I i Intensity of incident light, 1 sample path length, 1 c coherent length, n, refractive index If phase matching condition A k =0 does not hold, I decreases, i.e., 1 m depends on the incident angle 0. m = 2 second harmonic generation (SHG) m=3 third harmonic generation (THG)... 

In order to assess the accuracy of the dynamic SDMRG technique, we have performed a series of model calculations we computed the dynamic linear polarizabilities (0(0 )) and third-order polarizabilities (7(0 , 01,0 )) corresponding to the third harmonic generation (THG), for the Hubbard and J7—V polyene-like chains of up to 20 sites with and without dimerizations (note that the dimerization parameter S reflects the degree of carbon-carbon bond-length alternation along the polyene chain nonzero S leads to alternating t and V values while zero 5 means uniform t and V). 

Figure 12. (A) Values of y(—3(u (u,(u,(u)/Afas a function of the number of double bonds Af for the model oligomer 6 [poly(DEDPM)] as measured by third harmonic generation at 1.9 jum. The solid line is a guide for the eye. (B) Plot of d[ln(y)]/d[ln(A/)] as a function of chain length for the data in A.

We measured the third harmonic generation (THG) of la-e using polystyrene matrices and variable laser wavelengths [136]. In order to understand the influence of the chain length on nonlinear optical properties, it is better to discuss the second hyperpolarizability y, which is a molecular parameter, than the macroscopic susceptibility which is a bulk quantity. For the determination of j/jesj, the imaginary part of the total third-order susceptibility j/res j of the films (thickness 50 and 212 nm) was taken. The result is depicted in Fig. 11.13 [136] in a double logarithmic plot of jy gs] versus the length L of the OPE chains I is a linear function of the number n of repeat units. (See Section 11.1.)... 

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