A twist sensor based on polarization-maintaining fibers with different cladding diameters

A fiber twist sensor using a Sagnac interferometer incorporating a tapered polarization-maintaining fiber (PMF) is proposed. The transmission properties of the sensor are investigated both theoretically and experimentally. Given the optoelastic effect, which depends on fiber geometry, the modal and group birefringences of the PMF can be controlled by applying different twist angles. The spectral wavelength shifts, free spectral ranges, and transmission losses of the original, microtapered, and etched PMFs were compared. Notably, the interference dips for the etched PMF move in opposite directions. As a result, the proposed PMF-based sensor could have multiparameter sensing applications