Fiber Optic Resonators for Angular Rate Sensors

Fiber-optic ring resonators can be used in various fields of science and technology as miniature sensors and sensors of physical quantities: an optoelectronic generator, a temperature and pressure sensor, biosensors, an angular rate sensor, etc. To determine the operating parameters of a measuring sensor, it is necessary to measure the resonant parameters with an acceptable accuracy. These parameters are free spectral range (FSR), width at half maximum (FWHM), finesse (F) and quality factor (Q-factor).We have fabricated and investigated resonators, each of which is a closed fiber cavity of two fused couplers. The authors managed to reduce the error caused by the nonlinearity by using a reference asymmetric Mach–Zehnder interferometer and applying the Hilbert transforms. Synchronous measurement of the resonant spectrum and the beat signal coming from the interferometer during tuning of the laser center frequency and subsequent signal processing in a mathematical package made it possible to reduce the relative measurement error of the resonator performance parameters from 15 to 0.5%. This technique makes it possible to measure not only operating parameters with good accuracy, but also to record the change in these parameters, which improves the accuracy of detectors and sensors based on optical resonators.