ABSTRACT
We report on a new time-resolved coherent Raman technique that is based on the generation of thermal gratings following a population change among molecular levels that is induced by stimulated Raman pumping. This is achieved by use of spatially and temporally overlapping intensity interference patterns generated independently by two lasers. When this technique is used in carbon dioxide, making use of transitions that belong to the Q branches of the v(1)/2v Fermi dyad, it is possible to investigate molecular energy transfer processes. A further unique feature of this method is spectral resolution that is better than that achieved by coherent anti-Stokes Raman scattering.
ABSTRACT
Time-resolved measurements of the fluctuating intensity of a multimode frequency-doubled Nd:YAG laser have been performed. For various operating conditions the enhancement factors in nonlinear optical processes that use a fluctuating instead of a single-mode laser have been determined up to the sixth order. In the case of reduced flash-lamp excitation and a switched-off laser amplifier, the intensity fluctuations agree with the normalized Gaussian model for the fluctuations of the fundamental frequency, whereas strong deviations are found under usual operating conditions. The frequencydoubled light has in the latter case enhancement factors not so far from values of Gaussian statistics.
ABSTRACT
Third-order difference-frequency generation of the type omega = 2omega(1) - omega(3) has been used to determine accurately the cubic nonlinearities of various crystals of the space group Fm3m. The samples were rotated under well-defined polarization conditions of the incoming fields of frequencies omega(1) and omega(3). Ratios of anisotropic to isotropic contributions have been derived, and an attempt has been made to obtain absolute nonlinear susceptibility data by comparison with BK7 glass.
