Simple phase noise measurement scheme for cavity-stabilized laser systems

TL;DR

This paper introduces a straightforward technique to measure residual fast phase noise in cavity-stabilized lasers by analyzing beat notes, enabling direct assessment without complex calibration, demonstrated on an external-cavity diode laser.

Contribution

The paper presents a simple, calibration-free method for residual phase noise measurement in cavity-stabilized lasers using beat note analysis.

Findings

Effective measurement of residual phase noise demonstrated

Method aligns well with in-loop error signal analysis

Applicable to various cavity-stabilized laser systems

Abstract

We describe a simple method for measuring the residual fast phase noise of a cavity-stabilized laser using the cavity as a reference. The method is based on generating a beat note between the laser output and the strongly filtered light transmitted through the cavity. The beat note can be directly analyzed without requiring further calibration of system parameters. We apply the method to measure the residual phase noise of an external-cavity diode laser (ECDL) locked to a reference cavity and compare the results with an analysis of the in-loop error signal of the feedback system.