Stable and high power 515-nm lasers for the space gravitational wave detector: DECIGO

Abstract

We have developed the frequency-stabilized lasers for gravitational wave detector DECIGO, whose short-term and long-term frequency stability is required to be df/f=10-15 level with the high output power of 10 W. The short- and long-term frequency stability is realized by using frequency reference of an iodine absorption signal at 515 nm. We made two Breadboard models to evaluate the frequency stability of the laser. The short-term frequency stability is improved to 30 Hz/√Hz at 1 Hz by suppressing the intensity noise of the laser at modulation frequency of 200 kHz, and long-term frequency stability also improved by suppressing residual amplitude modulation (RAM). For increasing the output power with keeping its frequency stability, a 2-stage cascade fiber amplifier has been developed. In the current presentation, we report the status of our frequency stabilized lasers and the schematic of its higher power unit.