Compact single-seed, module-based laser system on a transportable high-precision atomic gravimeter

Abstract

A single-seed, module-based compact laser system is demonstrated on a transportable $^{87}\text{Rb}$-based high-precision atomic gravimeter. All the required laser frequencies for the atom interferometry are provided by free-space acousto-optic modulators (AOMs) and resonant electro-optic phase modulators (EOMs). The optical phase-locked loop between the two optical paths derived from the same laser provides an easy frequency manipulation between two laser frequencies separated by the hyperfine frequency of 6.835 GHz using an AOM and an EOM, respectively. Our scheme avoids parasite Raman transitions present in the direct EOM modulation scheme (modulating directly at the frequency of the hyperfine splitting), which have detrimental effects on the accuracy of the gravity measurements. The optical phase-locked loop also provides a convenient way for vibration compensation through the Raman lasers' phase offset. Furthermore, the modular design approach allows plug-and-play nature on each individual optic module and also increases the mechanical stability of the optical systems. We demonstrate high-precision gravity measurements with 17.8 $\mu\text{Gal}$ stability over 250 seconds averaging time and 2.5 $\mu\text{Gal}$ stability over 2 h averaging time.