A phase-locked laser system based on modulation technique for atom interferometry

TL;DR

This paper presents a phase-locked laser system utilizing modulation and feedback control, achieving low phase noise suitable for atom interferometry and gravimetry applications.

Contribution

The paper introduces a novel laser system with phase modulation and feedback that reduces phase noise below existing optical phase-lock loop schemes for atom interferometry.

Findings

Phase noise stays below -125 rad^2/Hz above 500 kHz.

The system's sensitivity limit is lower than state-of-the-art schemes at short pulse durations.

The laser system is promising for future atom interferometry applications.

Abstract

We demonstrate a Raman laser system based on phase modulation technology and phase feedback control. The two laser beams with frequency difference of 6.835 GHz are modulated using electro-optic and acousto-optic modulators, respectively. Parasitic frequency components produced by the electro-optic modulator are filtered using a Fabry-Perot Etalon. A straightforward phase feedback system restrains the phase noise induced by environmental perturbations. The phase noise of the laser system stays below -125 rad2/Hz at frequency offset higher than 500 kHz. Overall phase noise of the laser system is evaluated by calculating the contribution of the phase noise to the sensitivity limit of a gravimeter. The results reveal that the sensitivity limited by the phase noise of our laser system is lower than that of a state-of-art optical phase-lock loop scheme when a gravimeter operates at short pulse duration, which makes the laser system a promising option for our future application of atom interferometer.