Robust single-sideband-modulated Raman light generation for atom interferometry by FBG-based optical rectangular filtration
Guochao Wang, YaNing Wang, Ying Kang, Huankai Zhang, Xu Zhang, Qixue Li, Xuan Li, Enlong Wang, Xiaoyan Yu, Aiai Jia, Shuhua Yan, Jun Yang, Lingxiao Zhu
Abstract
Low-phase-noise and pure-spectrum Raman light is vital for high-precision atom interferometry by two-photon Raman transition. A preferred and prevalent solution for Raman light generation is electro-optic phase modulation. However, phase modulation inherently brings in double sidebands, resulting in residual sideband effects of multiple laser pairs beside Raman light in atom interferometry. Based on a well-designed rectangular fiber Bragg grating and a plain electro-optic modulator, optical single-sideband modulation has been realized at 1560 nm with a stable suppression ratio better than -25 dB despite of intense temperature variations. After optical filtration and frequency doubling, a robust phase-coherent Raman light at 780 nm is generated with a stable SNR of better than -19 dB and facilitates measuring the local gravity successfully. This FBG-based all-fiber single-sideband-modulated Raman light source, proposed for the first time and characterized as robust, compact and low-priced, is practical and potential for field applications of portable atom interferometry.