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Ultrastabilized solid state laser for gravitational wave detection

We describe frequency stabilization of two laser-diode-pumped Nd:YAG lasers independently locked to two high-finesse Fabry-Perot cavities. The frequency noise is reduced to the shot noise limit of 0.37 mHz/(root)Hz at the error signal. A heterodyne beat note between two locked lasers is used to measure the frequency stability, and the beat linewidth of 16 Hz and the root Allan variance of 19 Hz at time interval of 3 ms are measured. A new scalable geometry of multi-LD-pumping for high power and TEM00 output solid state lasers have been developed. The principle of virtual point source clad pumping system is discussed in terms of analytical and numerical calculations. A prototype model was developed by using 32 X 1 W - fiber-coupled LD. The center core of 200 micrometers diameter of 2-mm YAG rod was excited efficiently. The transverse mode of output was controlled simply by changing the ratio of excitation volume to cavity mode volume. The high power version of 320 W pumping is designed and appear in the near future.