Sensitivity enhancement of a single-fiber Mach-Zehnder interferometer by sensitizing its interference length

This paper presents a simple and novel, to the best of our knowledge, methodology towards enhancement of the refractive index sensitivity of the single-fiber (SF) Mach-Zehnder interferometer (MZI) configuration, post-fabrication, over a relatively large range from 1.3344 RIU to 1.4532 RIU. A SF-MZI configuration, fabricated indigenously by non-adiabatic tapering of the silica fiber at two places separated by a distance of ∼3.6cm, is sensitized with induced birefringence by keeping weights on its interference region. By sensitizing the configuration, its refractive index (RI) sensitivity is enhanced from 20.24 nm/RIU to 84.68 nm/RIU, post-fabrication, validating the theoretical predictions. The proposed process for enhancing the RI sensitivity of the SF-MZI, presented for the first time, shall be useful for many applications.