Development of a high-power light source for large-scale cryogenic gravitational wave telescope (LCGT)

A 100-W, single-frequency laser system for a Japanese gravitational wave detection project is being developed. We constructed a 121-W Nd:YAG laser and investigated injection locking with a 2-W master laser. Unidirectional oscillation of the ring laser in the fundamental transverse mode was demonstrated by using an intra-cavity Faraday rotator. The intensity noise of the unidirectional ring laser was suppressed to the same level with the linear cavity. The slave cavity below the oscillation threshold was locked by a 2-W master laser. The main difficulty in injection locking was the large fluctuation of the slave cavity. We are now investigating the mode matching in order to achieve injection locking of the high-power laser.