Low-Coherence Homodyne Interferometer for Sub-Megahertz Fiber Optic Sensor Readout

Abstract

This study proposes a method for interferometric fiber optic sensor readouts. The method utilizes the advantages of the active homodyne demodulation technique and low-coherence interferometry. The usage of the tandem low-coherence interferometer enables modulating the reference interferometer without any changes to the sensor. This achieves high sensitivity, high stability, and a wide frequency band. A sensitivity of up to 0.1 nm (RMS) in the frequency range of 5 kHz is demonstrated by detecting acoustic signals with a fiber Michelson interferometer as a sensor.

Monolithically Integrated Michelson Interferometer Using an InGaAs/InAlAs Quantum Cascade Laser at λ = 4 µm

“…As one example, this is illustrated by a paper written in 2023 by Englert et al, in which wind velocities and directions in the Martian atmosphere have been determined [14]. Very recently, Michelson interferometers have also been utilized for exact failure location in extended optical fiber networks [15], high-resolution fiber optic sensor readout systems [16], detecting small volume/low concentration chemicals in a ring cavity laser [17], and absolute distance measurements using frequency combs [18,19], as well as tracking impact locations with a low-coherence Michelson interferometer [20].…”