An optical system for cryogenic temperature measurements

Fiber optics with a photo-imprinted Bragg grating have been studied for potential use as temperature sensors in cryogenic applications. Sensors were coupled with different metallic materials to improve the measurement sensitivity in the very low temperature region, i.e. 4.2-30 K. Various coatings were deposited on the external fiber surface, and full characterization of the tested sensors is given in the paper.