Study of optical fiber cryogenic temperature sensor for quench detection of high temperature superconductors

In this study, a new processing design of an optical fiber cryogenic temperature sensor (OFCTS) is presented. The sensing unit is constituted by NaYF₄:Yb³⁺, Er³⁺@NaYF₄ core-shell upconversion nanocrystals-polymethyl methacrylate (UCNCs-PMMA) nanocomposites. The coupling is achieved by fiber fusion in the embodiment. The relative sensitivity of the OFCTS can reach the maximal value 13.241×10^-3 K^-1 at 80 K in a cryogenic environment, and stability is good with a standard deviation of 0.012. Research results show that the proposed OFCTS has good temperature responses at the cryogenic environment, and has a great potential of the superconducting application for generator, transmission line, maglev train and quantum interferometer.