# Carrier frequency modulation of an acousto-optic modulator for laser stabilization

## TL;DR

This paper introduces a novel laser stabilization technique using carrier frequency modulation of an acousto-optic modulator, creating a simple, versatile method suitable for atomic and cavity-based references.

## Contribution

The authors present a new method employing AOM carrier frequency modulation to generate a dispersion signal for laser stabilization, applicable with minimal setup and broad reference compatibility.

## Key findings

- Successfully locked a diode laser to rubidium transition
- Demonstrated agreement between measured and theoretical signals
- Applicable to atomic and cavity-based stabilization schemes

## Abstract

The stabilization of lasers to absolute frequency references is a fundamental requirement in several areas of atomic, molecular and optical physics. A range of techniques are available to produce a suitable reference onto which one can 'lock' the laser, many of which depend on the specific internal structure of the reference or are sensitive to laser intensity noise. We present a novel method using the frequency modulation of an acousto-optic modulator's carrier (drive) signal to generate two spatially separated beams, with a frequency difference of only a few MHz. These beams are used to probe a narrow absorption feature and the difference in their detected signals leads to a dispersion-like feature suitable for wavelength stabilization of a diode laser. This simple and versatile method only requires a narrow absorption line and is therefore suitable for both atomic and cavity based stabilization schemes. To demonstrate the suitability of this method we lock an external cavity diode laser near the $^{85}\mathrm{Rb}\,5S_{1/2}\rightarrow5P_{3/2}, F=3\rightarrow F^{\prime}=4$ using sub-Doppler pump probe spectroscopy and also demonstrate excellent agreement between the measured signal and a theoretical model.