In-Line Interferometric Temperature Sensor Based on Dual-Core Fiber

In this paper, we proposed an in-fiber Mach-Zehnder temperature sensor based on a dual-core fiber (DCF) in which one core, working as the sensing arm, is suspended in an embedded fluidic channel filled with silicone oil, while the other one, working as the reference arm, locates eccentrically in the DCF. Temperature variations would change the refractive index of silicone oil infiltrated as well as the effective index of the guided mode in the suspended core, thus shifting the interference spectra. Both experiments and numerical simulations were carried out to characterize the sensor. The spectrum shifts measured experimentally agreed well with the theoretical results. Experimental sensitivity of the sensor using a DCF infiltrated with ~20 cm-long silicone oil was found to be as high as −1.42 nm/°, comparable to those of the SPR fiber sensors and other interferometric sensors. The measuring range of the sensor was more than 120°. The proposed sensor could be easily fabricated with good robustness and stability, which makes the sensor promising for applications such as environment and architecture monitoring.