Simultaneous measurement of displacement and temperature based on thin-core fiber modal interferometer

An optical-fiber sensor based on a thin core fiber (TCF) has been proposed and experimentally demonstrated for simultaneous measurement of displacement and temperature. This in-line sensor consists of a segment of TCF between two segments of single-mode fibers (SMFs), and the interference between the core mode and the cladding mode of the TCF occurs. The transmission spectral responses to displacement as well as environmental temperature have been investigated. Experimental results show that the displacement sensitivities of –0.01028 nm/μm and −0.01535 nm/μm for a displacement range of 0–650 μm have been achieved, and the corresponding temperature sensitivities reach about 0.00942 nm/°C and 0.00493 nm/°C within a large temperature range of 20–90 °C, respectively. The proposed sensor exhibits such advantages as simple structure, compact size, ease of fabrication, high sensitivity, etc. Therefore, it has potential applications in accurate multi-parameter measurements.