Abstract
In this thesis, Lithium Triborate (LBO) and Beta-Barium Borate (β-BBO) crystals were used for generation of second and fourth harmonics of the output of high-power ytterbium-doped dual stage Master-laser-fiber-amplifier (MOFA) at the fundamental wavelength of 1064 nm. The pulse duration of the amplifier output is around 10 ps. An acousto-optic modulator (AOM) was used to modulate the duration of pulse bursts before the fiber amplifier. We found that stimulated Raman scattering (SRS) and self-phase modulation (SPM) are the most important nonlinearities limiting the performance of whole laser system. In order to reduce the nonlinearities in the fiber amplifier and achieve the highest average power at 266nm, several schemes were implemented: - the lengths of the active fibers in the fiber amplifier stages were optimized; - the polarized launch conditions of the fiber amplifier were controlled such that its spectral width was minimized; - the repetition rate and duty circle of pulse bursts were adjusted to maximize the doubling and quadrupling efficiencies; We demonstrated that the spectral bandwidth of the amplifier output can be narrowed from 6 nm to 1 nm when the shorter active fibers are employed and the polarization launch conditions are varied from linear to circular states. Also, a pulse-burst repetition rate of 52.5 MHz, and burst duty circle of 0.35 are determined to be optimal for extraction of the maximum peak power while keeping amplified spontaneous emission below the acceptable level. This allows us to generate the maximum average power of the UV pulses at 266 nm over 200 mW when the power of the fundamental IR pulse was 28 W.