Temperature sensing based on a singlemode-multimode-singlemode (SMS) fiber structure with a graded index
multimode fiber (GI-MMF) type using an intensity-based interrogation has been investigated numerically and
experimentally. The effect of temperature on the SMS fiber structure with the MMF-GI type was modeled using a modal
propagation analysis (MPA). The SMS fiber structures for temperature sensor was fabricated and tested with the MMF
length of 57 mm. It is demonstrated experimentally, and supported with numerical results, that the sensor showed a
sensitivity of 0.063 dB/°C with a temperature measurement range of 175-325°C. This sensor offers simple configuration
and low cost of fabrication for the temperature measurement applications.