Abstract

Gravitational Wave (GW) is very small temporal variation of space distortion which is caused from the change of enormous mass such as inspiral and merger of black hole binaries, explosion of supernovae, and the inflation in the early universe. In order to detect GW directly, long-baseline laser interferometers have been developed by many countries and, at long last, the first direct detection of GW was achieved by the ground-based Advanced LIGO detectors [1]. In Japan, not only the ground-based GW detector, KAGRA [2], but also the space GW detector, DECIGO (DECi-hertz Interferometer Gravitational wave Observatory) [3] have been promoted which is a 3-km triangle shaped laser interferometer with the detection band between 0.1 Hz and 10 Hz. We have developed space borne frequency and the intensity stabilized lasers for DECIGO whose required frequency and intensity noise level are δf =1 Hz/√Hz and δI/I =1×10^-8 /√Hz at observation band around 1 Hz, respectively, and the high power output power up to 10 W is also required.

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