Degenerate four-wave mixing DFWM

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.)...

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... 

The third order optical susceptibility was measured by degenerate four-wave mixing (DFWM). A single pulse at 1.064 pm with a full width at half maximum of 35 ps was selected from the output of a passively mode locked Nd/YAG laser and split into three... 

In the degenerate four wave mixing (DFWM) experiment the third-order susceptibility 3)(-tt>,tt>,-CL>,CL>) with degenerate frequencies can be determined [22]. This nonlinear susceptibility is directly proportional to the nonlinear refractive index n2, which is used to describe optically induced refractive index changes. An advantage of this technique is the possibility to record the temporal shape of the third-order nonlinear optical signal. 

Another difficult experiment is degenerate four-wave mixing (DFWM), which measures (—co a>, —a>, a>) (Fig. 11.35). 

Measurements of x(3>(—cu to, to, —to) by backward-wave degenerate four-wave mixing (DFWM). Two pump beams of equal intensity A, and l2 and opposite phase meet at the sample and, with a weaker probe beam /3, cause the formation of an emitted beam /4. M1, M2, M3 and M4 are mirrors BS1, BS2, and BS3 are beam splitters. 

Table 9.3 Third harmonic generation (THG) and degenerate four wave mixing (DFWM) non-linear optical coefficients of conjugated polymers.

Degenerate four-wave-mixing (DFWM, Section 10.2.3) in conjugated polymers has also been explored. Its use in optical image correlation has been demonstrated using Durham-route PAc and similar polymers. The very large optical non-linearity of PAc, Table 9.3, and the fast electronic response allow correlation to be performed with sub-picosecond laser pulses. The poor stability of PAc prevented this laboratory demonstration being turned into a practical device. 

Degenerate four-wave mixing (DFWM) Degenerate four-wave mixing (DFWM) is another well-known nonlinear technique based on third-order nonlinear susceptibility similar to CARS... 

Banerjee and Harbola [69] have worked out a variation perturbation method within the hydrodynamic approach to the time-dependent density functional theory (TDDFT) in order to evaluate the linear and nonlinear responses of alkali metal clusters. They employed the spherical jellium background model to determine the static and degenerate four-wave mixing (DFWM) y and showed that y evolves almost linearly with the number of atoms in the cluster. 

Four-Wave Mixing is the optical process where the nonlinear interaction between three beams generates a fourth beam. When the frequencies of the input waves are different, new frequencies are generated. The case of equal frequencies is called degenerate four-wave mixing (DFWM). 

Tlie usual experimental techniques developed to study the optical Kerr effect in materials have already been described in a preceding chapter of this book. We only mention here the methods which have especially been used for nanocomposite materials as colloidal solutions or thin films Degenerate four-wave mixing (DFWM) and optical phase conjugation, which provide the modulus of x only and may be completed by Interferometry techniques to get its phase as well, optical limiting, optical Kerr shutter, and z-scan, which is probably the most common technique used in recent years due to its ability to provide simultaneously the nonlinear refraction and absorption coefficients of the same sample point [118],... 

Third-order NLO properties have been described for liquid-crystalline phthalocyanine and porphyrin complexes. The values for the meso-genic cobalt(II), nickel(II), copper(II), zinc(ll) and vanadyl complexes of 5,10,15,20-tetrakis(4-w-pentadecylphenyl)porphyrin have been measured in benzene solution by the technique of degenerate four-wave mixing (DFWM) at 532 nm. The values varied between 1.5 and... 

Y(-co to, to, -to) Intensity Dependent Refractive Index IDRI Degenerate Four Wave Mixing (DFWM)... 

---