Laser conditioning of LaF(3)/MgF(2) dielectric coatings at 248 nm.

Highly reflective LaF(3)/MgF(2) systems for a wavelength of 248 nm on MgF(2) and crystalline quartz substrates were investigated. The influence of laser conditioning on damage threshold and absorptance was remarkable in those coatings that had a high initial absorptance. Monitoring with a laser calorimeter revealed the conditioning effect to be a function of the irradiation dose rather than of energy density or pulse rate. Furthermore, x-ray photoelectron spectroscopy and transmission electron microscopy investigations showed that conditioning induces stoichiometric and structural changes in the multilayers, especially in near-surface sublayers, whereas scanning electron microscopy and atomic force microscopy investigations indicated that the surface remains unchanged.

82% Efficient continuous-wave frequency doubling of 1.06 microm with a monolithic MgO:LiNbO(3) resonator.

We describe a frequency-doubling monolithic standing-wave resonator made of MgO:LiNbO(3) with dielectric mirror coatings for impedance matching near 100 mW input power and near-optimum nonlinear coupling. An external conversion efficiency of 82% has been achieved.

Single-shot autocorrelator for KrF subpicosecond pulses based on two-photon fluorescence of cadmium vapor at lambda = 508 nm.

By excitation of cadmium vapor with a high-peak-power KrF excimer laser pulse, fluorescence of an atomic transition at lambda = 508 nm is induced by a two-photon ionization process followed by fast recombination. The nonlinear response of the medium is used to develop a simple single-shot autocorrelator for subpicosecond KrF excimer laser pulses operating down to intensities of less than 10(9)W/cm.(2) We have measured 360-fs (FWHM) pulses at lambda = 248 nm with a time resolution of 15 fs.