Harmonic Generation and Long-Range Optical Binding of Aerosols.

Abstract

This dissertation presents the results of two major optical experiments. The first is the generation of continuous-wave ultraviolet light from an infrared pump laser by fourth harmonic generation in a lithium niobate whispering gallery resonator. The UV fourth harmonic (as well as the near-infrared second and visible third harmonics) is observed at input powers as low as 200mW, and is detected on a spectrum analyzer and photographed directly after outcoupling from a diamond prism. The emitted light is tunable over a pump range of 1535 to 1545nm, due to quasi-phase matching with a variable crystal poling period and high order modes in the resonator. This work extends previously observed second harmonic generation in similar devices to wavelengths near 385nm, demonstrating a compact, coherent UV source, and providing a first step toward high harmonic generation at CW operation. The second experiment is the observation of long-range optical binding of aerosols in a vertical Gaussian beam optical trap. We demonstrate optical binding of 7-25micron diameter objects in a weakly focused Gaussian beam trap. In contrast to prior work in viscous liquids, the observed optical interactions take place in air, and without the use of interference techniques to create an optical potential landscape.