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Second- and third-order optical nonlinearities of L-threonine amino acid crystals grown from aqueous solution are investigated in this work. The absorption spectra indicate a good transparency between 250 and 1500 nm. Refractive indices were measured as a function of temperature and wavelength, allowing the determination of the thermo-optic and Sellmeier equation coefficients. Phase-matching curves for second harmonic generation from radiation at 1.064 μm were obtained. The conversion efficiency was measured along the entire phase-matching loci and its maximum value was found to be comparable to that of KDP. The nonlinear refractive index n2, measured through the Z-scan technique with femtosecond pulses, is of the order of 10−20 m2/W. [Copyright &y& Elsevier]

We have used the white-light continuum (WLC) Z-scan technique to determine the degenerate two-photon absorption (2PA) cross-section spectrum of poly(2-methoxy-5-(2′-ethylhexyloxy)-1,4-phenylenevinylene). The results obtained show good agreement with those employing a single-wavelength source, although much faster because of the wavelength multiplexing introduced by the use of a broadband source. The improved spectral resolution of the WLC Z-scan allowed the observation of a 2PA peak around 675 nm, a subtle feature in the nonlinear spectrum that could be fitted using a sum-over-states model. The WLC Z-scan technique has proved to be an important tool to determine the 2PA spectrum of polymers. [ABSTRACT FROM AUTHOR]

Presents a study of the control of the interaction of light with an atom during ionization. Improvement of the efficiency of X-ray generation by an order of magnitude; How the shape of ultrashort light pulses may be tailored to this end; Control of the interaction between different orders of nonlinear processes by tuning the spectral characteristics of emitted radiation.

Studies dynamic optical nonlinearities with pulse trains. Extension of the Z-scan technique; Discrimination between fast and accumulative nonlinearities.