Compact in-reflection fiber interferometer using thermally expanded core fiber and single-mode fiber and its applications as temperature and refractive index sensors

摘要

We propose and experimentally demonstrate a compact in-reflection Mach-Zehnder fiber interferometer and applied the proposed device to temperature and refractive index sensing. By splicing a short section of an uncoated single-mode fiber with a thermally expanded core fiber, we obtained an interference pattern in the reflection spectrum of the device due to the effective index difference between the core mode and the cladding modes of the SMF which can be excited and re-collected due to the mode field mismatch at the splice point. We then demonstrate the use of this interferometer for temperature and refractive index sensing.