Highly frequency-stabilized laser for space gravitational wave detector DECIGO/DPF

Direct detections of gravitational wave (GW) by using a long-baseline laser interferometer have been tried in many countries. In Japan, a space-GW detector named DECIGO (Deci-hertz interferometer Gravitational wave detector), and its milestone mission DPF (DECIGO pathfinder) has been promoted. We have developed a spaceborne highly frequency-stabilized light source for DECIGO and DPF with high mechanical stability, long-term stable operation, high-efficiency and compactness. The frequency of an Yb doped fiber DFB laser at 1030 nm was locked to the saturated absorption signal of the iodine molecule (I 2 ) at 515 nm. We have developed the breadboard model 1 (BBM1) of the I 2 stabilized Yb:fiber laser, which was installed on a 550x300x20-mm aluminum plate. The frequency noise of the laser was suppressed down to 0.4 Hz/Hz 1/2 at 1 Hz which was evaluated from the frequency error signal. In the present paper, we will report the details and performance of the BBM1 of the light source for DECIGO and DPF.