Passive, free-space laser gyroscope

TL;DR

This paper introduces a passive laser gyroscope design that uses external laser beams to track a sensing cavity, avoiding lock-in effects and achieving sensitivity comparable to active gyroscopes, with potential applications in seismic and gravitational wave detection.

Contribution

The paper presents a novel passive laser gyroscope topology that is simpler to construct and free from lock-in effects, matching the sensitivity of active designs.

Findings

Achieves sensitivity comparable to active laser gyroscopes.

Avoids lock-in effects present in active designs.

Uses commercially available components for construction.

Abstract

Laser gyroscopes making use of the Sagnac effect have been used as highly accurate rotation sensors for many years. First used in aerospace and defense applications, these devices have more recently been used for precision seismology and in other research settings. In particular, mid-sized (~1 m-scale) laser gyros have been under development as tilt sensors to augment the adaptive active seismic isolation systems in terrestrial interferometric gravitational wave detectors. The most prevalent design is the "active" gyroscope, in which the optical ring cavity used to measure the Sagnac degeneracy breaking is itself a laser resonator. In this article, we describe another topology: a "passive" gyroscope, in which the sensing cavity is not itself a laser but is instead tracked using external laser beams. While subject to its own limitations, this design is free from the deleterious lock-in effects observed in active systems, and has the advantage that it can be constructed using commercially available components. We demonstrate that our device achieves comparable sensitivity to those of similarly sized active laser gyroscopes.