  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 an
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 proposed all-fiber single-sideband-modulated Raman light
source, characterized as robust, compact and low-priced, is practical and
potential for field applications of portable atom interferometry.
