Optical path length sensor

Abstract

An optical path length sensor for sensing a physical quantity of an external source comprises a plurality of lasers, each comprising an optical resonator and a gain medium (31) to generate a laser beam (32a, 32b) in the optical resonator. At least one of the optical resonators is configured to modulate a light frequency of the laser beam when exposed to an external source. The sensor further comprises: a common carrier (44) in which the optical resonator is arranged; and a device configured to receive light from the plurality of lasers and determine a difference between light frequencies of the laser beams. In another aspect, the optical path length sensor includes a plurality of interferometers, each interferometer being an asymmetric Mach-Zehnder interferometer or an asymmetric Michelson interferometer, where at least two of the plurality of interferometers have different optical path length imbalances.

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