Optical Kerr gating

Contrary to the above-described detection methods, fluorescence up-conversion and optical Kerr gate techniques readily achieve picosecond/femtosecond time resolution (Ippen and Shank 1975 Shah 1988 Takeuchi and Tahara 1998), because they are in the pump-probe measurement, in principle. 

FIGURE 3.2 Principle of (a) fluorescence up-conversion and (b) optical Kerr gate. 

Ippen, E. R, and Shank, C. V. 1975. Picosecond response of a high-repetition-rate CS2 optical Kerr gate. Appl. Phys. Lett. 26 92. 

In the optical Kerr gate experiment6 (Fig. 5), the sample is subjected to a linearly polarized pump beam that induces optical birefringence (and... 

Fig. 5. Setup of an optical Kerr gate experiment. (Adapted with permission from R. L. Sutherland, Handbook of Nonlinear Optics, 1996, p. 429. Copyright 1996 Marcel Dekker, New York).

The techniques that have been developed to probe the kinetics of energy transfer processes In materials on a picosecond time scale can be divided into three general categories. They are the optical Kerr gate, the excite and probe technique, and the streak camera technique. 

Arzhantsev S. and Maroncelli M. (2005), Design and characterization of a femtosecond fluorescence spectrometer based on optical Kerr gating , Appl. 

The Optical Kerr Gate (OKG) method allows measurement of x by studying the polarization change of a probe beam, propagating through the system where the optical birefringence is induced through an intensity-dependent refractive index. The method was described by Ho [69]. 

Finally, we should enquire as to whether or not it is reasonable to expect a linear response in describing the rotational diffusion of dipoles in the presence of a very strong local field, such as presented by the excess electron. The time window of the optical Kerr gate driven by a picosecond laser pulse depends on the relaxation of the molecules of the Kerr medium from an aligned orientation to an isotropic spatial distribution, once the applied optical field is switched off. For many liquids this relaxation time r is the low field limit, namely, the Debye time. We might anticipate an asynunetry in the temporal response 5 (0 of... 

The real part of the susceptibility, Rex was determined using the optical Kerr gate technique. The experimental arrangement is shown in Fig. 4. 

The optical Kerr gate (OKG) is a process that arises due to optically induced birefringence caused by a nonlinear phase shift. The NLO polarization for the OKG can be expressed as [2,3]... 

FIGURE 49.8. Schematics of experimental arrangement of the optical Kerr gate measurement. 

To study the carrier and vibrational relaxation dynamics, mode-locked laser systems, which provide femtosecond pulses and fast and sensitive detection systems are necessary. For detection, streak cameras are used for measurements with time resolution in the subpicosecond range or CCD cameras for time-integrated measurements. For the latter, time resolution can be achieved by using optical Kerr gates or upconversion [266,268]. In general, the two mainly used optical detection mechanisms for coherent phonons (optical, acoustical, or LO-plasmon coupled modes) are the pump/probe [280-285] and the four-... 

Optical Kerr Gate and Pump-Probe Measurements... 

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