Bent Fiber Interferometer

We report a novel fiber-optic interferometer based on Mach-Zehnder interferometer (MZI) from a bent single-mode fiber (SMF) and experimentally demonstrated that it can be used as a fiber-optic refractometer. The interferometer has a simple structure including a standard SMF with a bare fiber semicircular bending region of a given diameter. A fiber MZI is formed by the different optical paths taken by the core and cladding modes from the designed bending fiber structure. We also realize a dual-channel interferometer by using a 9 and 11 mm bending diameter fiber structure and measure the refractive index of the ambient environment by monitoring the wavelength shift of the resonance dips in its transmission spectrum. Additionally, we investigate the relationship between the wavelength shifts of the resonant dips with temperature changes. This dual-channel interferometer can be potentially used for simultaneous measurement of dual chemical parameters.