Cladding modes’ interference in MM-tapered SM-MM fiber devices: Experimental demonstration of a high-sensitivity temperature sensor

Here, we report our experimental demonstration of a high-performance temperature sensor fabricated by cascading dissimilar multimode fibers and tapered single mode fiber coated with an index-matching gel of high thermo-optic coefficient. The output power is recorded under varying temperature conditions of the coated material. Besides wavelength-shifting based multimode interferometer sensor, here a unique methodology is adopted where an intensity based fiber temperature sensor is realized. Our optimized design yields a temperature measurement sensitivity of 8.1253 µW/^°C, accuracy of $\pm$ 0.9 ⁰C, response time of 392 ms and resolution of 0.1 ⁰C within the range of 29 °C to 64 °C. Analytical mode overlap and Ansys Lumerical simulation validate experimental results, affirming the method's effectiveness.