Robust single-sideband-modulated Raman light generation for atom interferometry by FBG-based optical rectangular filtration

TL;DR

This paper presents a robust, compact, and cost-effective all-fiber single-sideband Raman light source at 780 nm, achieving high suppression of unwanted sidebands and stable operation suitable for portable atom interferometry.

Contribution

It introduces a novel FBG-based optical rectangular filtration technique for stable single-sideband modulation at 1560 nm, enhancing Raman light generation for atom interferometry.

Findings

Suppression ratio better than -25 dB despite temperature variations

Stable SNR of better than -19 dB for Raman light

Successful measurement of local gravity using the developed source

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 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.