Polarizing light source of high beam quality and variable duration for KrF laser using stimulated Brillouin scattering techniques

摘要

An experimental polarizing light source setup of high beam quality and variable-duration for KrF laser of the master- oscillator-power configuration, using stimulated Brillouin Scattering technique, is being built up. A design and experimental optimization for cavity type of the master oscillator utilizing an EMG101 KrF laser were made as a first step of the whole setup. The 1.23 m long oscillator cavity is formed by a 10 m rear concave full reflectivity mirror and flat quartz output coupler with selected reflectivity: 60%, 73%, 82% or 96%, and with choosing one of three intracavity aperture diameter: 1.1 mm, 1.5 mm and 2.0 mm, respectively. We have measured pulse energy and pulse width of the whole laser spot size output. The pulsewidth is 13.6 ns, 16.4 ns, 10.8 ns and 8.8 ns corresponding to reflectivity of front mirror 60%, 73%, 82% and 96%, respectively. We also measured seed beam outputs and seed beam divergences for the four kinds of reflectivity of front mirror and three kinds of iris diameter. As viewed from the sufficient polarizing output and sufficient high beam quality, the results for optimizing of oscillator cavity types is suitable reflectivity of front mirror of R $LSEQ 73% and suitable diameter of 1.5 mm with beam quality near 2.5$MUL diffraction limited. The further steps of the building the whole above described experimental setup are undergoing.