Studies on Nonlinear Physics and Application Technology of Thin-Slice Solid-State Lasers with Coated End Mirrors

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The following main results have been obtained through studies on nonlinear physics and application technology using laserdiode (LD) pumped thin-slice solid-state lasers.1. Pattern formations in LD-pumped thin-slice solid-state lasers(1) Effects of surface roughness of reflective ends and pump-beam spot size on lasing pattern formations were studied systematically in wide-aperture thin-slim solid-state lasers with LD pumping. Such curious lasing patterns as quantum billiard-like modes, composite lattice modes and speckle modes were found experimentally.(2) Segregations into local transverse modes' and associated high-speed intensity modulations inclnding chaos were found in conventional Nd. : YAG ceramic lasers whose average grain size is several tens of microns. These phenomena were well reproduced theoretically.(3)The inherent problem in ceramic lasers was solved in the following way (i) The selective excitation of Ince-Gaussian lasing modes with learn diameters sufficiently larger th … More an grain sizes ; (ii) The use of micro-grained ceramic lasers with average grain size of few microns. In both cases, stable oscillations without segregations into local modes were realized.(4)The Lapumping method for controlled generations of higher order Ince-Gaussian modes in microchip solid-state lasers was developed and formation of various types of novel optical vortices was realized toward manipulating motions of small paricles.2.LD-pumecl self-mixing thin-slice solid-state laser metrology(1) We increased the optical sensitivity by two-orders of magnitude by improving devices in the frequency-shift feedback scheme.(2) We realized real-time vibrometry of 1-nm amplitude and quick sizing of small particles in water whose concentration is below 1 ppm in the particle diameter range of 80-500mn. The three-dimensional real-time vibrometry of 1-nm-amplitude was realized by usinghe carrierfrequency multiplexing method which we developed. The overall dynamics of Brownian particles was captured for the fa-A time by the FM demodulation circuit.(3) We applied our self-mixing laser metrology to flow measurements and quick measurements of flow velocity and dynamic viscosity were successfully demonstrated. Also, the detection of small particles in the flow was done under the concentration limit of 0.01ppm for 262-nmpolystyrene latex spheres. Less