Ultra-high Sensitive Temperature Sensor Based on Multimode Fiber Mach-Zehnder Interferometer

We propose an ultra-high sensitive temperature sensor based on multimode fiber (MMF) Mach-Zehnder interferometer (MZI). The multimode fiber MZI is composed of a short section of MMF inserting between another two pieces of MMFs with large lateral offset. The sensing head is packaged in a capillary which is filled with glycerol-water solution. At the offset splice interface, part of the light in the lead-in MMF is coupled into the glycerol-water solution around the sensing MMF and the remainder propagates along the cladding of the sensing MMF. Due to the large thermo-optic coefficient of the glycerol-water solution, the transmission spectrum of the MMF-based MZI shift quickly with temperature variation. Experimental results show that the temperature sensitivity is as high as 8.23 nm/degrees C.