A Chalcogenide Multimode Interferometric Temperature Sensor Operating at a Wavelength of $2~\mu\text{m}$

This paper investigated the fabrication of a singlemode-multimode-singlemode fiber structure based on a chalcogenide (As
₂
S
₃
and As
_x
S
_1-x
) multimode fiber sandwiched between two standard silica singlemode fibers using a commercial fiber fusion splicer. The temperature dependence of this hybrid fiber structure was investigated and a first proof of concept showed that the hybrid SMS fiber structure has an average experimental temperature sensitivity of circa 84.38 pm/°C over a temperature range of 20 °C~100°C at the wavelength range around 2 μm. The measured results show a general agreement with numerical simulations based on a guided-mode propagation analysis method. Our result provides a potential platform for the development of compact, high-optical-quality, and robust sensing devices operating at the midinfrared wavelength range.