A high sensitivity asymmetric double tapered fiber interference sensor

A high sensitivity micro/nano-fiber sensor with asymmetric double tapered structure based on Mach-Zehnder interferometer (MZI) was designed for refractive index (RI) and humidity measurements. The sensor is composed of two different lengths tapered region fabricated in a single-mode fiber, which demonstrated higher sensitivity and better integration with material compared to conventional double tapered fiber sensor. The results showed that the RI sensitivity of the fabricated sensor was 68.6 nm/RIU with the RI ranged from 1.348 to 1.403. Furthermore, the sensing region was deposited with graphene for humidity detection, and the graphene has exhibited great enhancement in terms of sensing performance. The obtained humidity sensitivity of the fabricated sensor was 68.7 pm/%RH with the environment humidity ranged from 50 to 90 %. This work provides a new strategy for designing optical fiber sensor by double tapered fiber sensor, which exhibited the immense potential of tapered optical fiber sensor for future advancements.