Highly sensitive RI and temperature sensor based on an asymmetric fiber coupler

We propose and demonstrate a highly sensitive refractive index (RI) and temperature sensor based on an asymmetric fiber coupler (AFC). The AFC was fabricated by weak fusion of a pre-stretched single-mode fiber and a few-mode fiber. An ultra-sensitivity RI can be achieved near the dispersion turning point (DTP). The proposed RI sensor achieves a high RI sensitivity of -10,662.4 nm/RIU within the RI range of 1.31-1.35. By packaging the AFC into polydimethylsiloxane (PDMS), the temperature sensitivity reaches 11.44 nm/degrees C. The proposed AFC with high RI and temperature sensitivity can be potentially used in the field of chemical monitoring, biochemical detection, and clinical diagnosis. (C) 2022 Optica Publishing Group