Optical Fiber Sensors: introduction to the feature issue.

This special issue contains a collection of papers on optical fiber sensors that were originally presented and published in a more succinct form in conjunction with the 27th International Conference on Optical Fiber Sensors (OFS) held in Alexandria, Virginia, United States, from 29th August to 2nd September, 2022.

Optical frequency dependence of the light shift effect for vector magnetometry with cesium.

Atomic vapor magnetometers have demonstrated very high sensitivity to the magnitude of the magnetic field. Vector field measurements are possible using bias fields applied to the vapor. For remote operation, the bias field can be generated using the optical light shift (LS) effect created with an optical beam delivered through optical fiber.

Optical phase response to temperature in a hollow-core photonic crystal fiber.

Analysis of previous measurements of thermal phase sensitivity in hollow core photonic crystal fibers is presented with additional new corroborating measurements, resolving a discrepancy in previously reported results. We extend an existing derivation of thermo-mechanical phase sensitivity in solid- and hollow-core photonic crystal fiber to also include kagome lattice photonic crystal fibers. Measured thermal phase response is shown to agree with theoretical prediction to within a few percent.

Crack detection in riveted lap joints using fiber laser acoustic emission sensors.

Fiber laser ultrasonic sensors are demonstrated to be capable of measuring acoustic emission generated by cracks in aluminum panels. A single laser sensor is integrated into a riveted lap joint, which is subject to accelerated fatigue. Acoustic emission generated by crack formation in the panel in addition to other acoustic events due to fretting within the joint are clearly resolved by the laser sensor.

Noise induced in optical fibers by double Rayleigh scattering of a laser with a 1/fν frequency noise.

We study, theoretically and experimentally, intensity noise induced by double Rayleigh scattering in long optical fibers. The results of the theoretical model are compared to experimental results performed with a high-coherence-length laser with a frequency noise spectrum that is dominated by 1/fν noise. Excellent quantitative agreement between theoretical and experimental RF spectra were obtained for frequencies as low as 10 Hz and for fiber lengths between 4 and 45 km.