Wavelength-Dependent Temperature Assessment Using Hetero-Core Fiber Sensors

This work presents a detailed and methodical evaluation of a widely established configuration utilizing hetero-core spliced systems for temperature sensing. Employing multimode-single-mode-multimode (MSM), temperature measurements in the range of 20–80 °C with varying wavelengths of source have been conducted. Through a basic intensity interrogation technique, the sensing performances have been assessed under varying infrared wavelengths, viz., 910, 1050, 1450, and 1550 nm. Notably, the transmission loss profile registers better sensitivity as well as linearity in case of 910 nm as compared with other wavelengths. The assessment of temperature remains fairly stable in the near infra-red region of wavelength. Towards higher wavelength, the transmission loss shows decline from linearity-albeit with pronounced decline magnitudes. Apart from this, the data suggests that different wavelengths interact differently with the fiber core and the surrounding medium, which affects the phase or intensity changes that are fundamental to temperature sensing.