Deployment of fibre segment interferometry in a high-temperature superconducting magnet

Measurements from optical fibre interferometers incorporated within a superconducting magnet coil, recorded during energization, are presented. The interferometers were formed between low reflectivity (0.01%), broad bandwidth (10 nm) in-fibre reflectors and were interrogated using the principles of range resolved interferometry, where the retuned signals from the interferometers addressed by a sinusoidally modulated DFB laser diode were demodulated using a quadrature processing technique. The demonstrated low noise (0.3 nε/√Hz), high resolution measurement capability indicates the significant potential for fibre segment interferometry for multiplexed strain measurement in cryogenic systems.