Length control of an optical resonator using second-order transverse modes

TL;DR

This paper introduces a simple, cost-effective method for stabilizing a laser to an optical cavity by using interference signals from higher-order modes, which is less sensitive to beam jitter and limited by quantum noise.

Contribution

The paper proposes a novel technique utilizing second-order transverse modes for cavity locking, enhancing stability and reducing sensitivity to beam jitter compared to existing methods.

Findings

Technique is simple and inexpensive.

Error signals are derived from mode interference.

Performance limited by quantum shot-noise.

Abstract

We present the analysis of an unorthodox technique for locking a laser to a resonant optical cavity. Error signals are derived from the interference between the fundamental cavity mode and higher-order spatial modes of order two excited by mode mismatch. This scheme is simple, inexpensive and, in contrast to similar techniques, first-order-insensitive to beam jitter. After mitigating sources of technical noise, performance is fundamentally limited by quantum shot-noise.