In-fiber Mach-Zehnder temperature sensor using silicone-oil-filled 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 reference arm, is located in the center of fiber and the other core, working as the sensing arm, is suspended in an embedded fluidic channel partially filled with silicone oil. Temperature variations would mainly change the refractive index of the silicone oil and therefore the effective index of the guided modes in the suspended core, while the guided modes in the center core were barely affected. Phase difference between guided modes in the two cores would be accumulated along the DCF, thus shifting the interference spectrum of the sensor. 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 DCF sensor filled with 33.5-cm-long silicone oil was found to be as high as −2.18 nm/°C, comparable to that of other interferometric sensors. 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.