Highly compact vector bending sensor with microfiber-assisted Mach-Zehnder interferometer

摘要： A low-cost and highly compact fiber-optic vector bending sensor component is proposed and experimentally demonstrated for vector bending sensing. A segment of microfiber tapered from standard single-mode fibers (SMFs) is spliced between two SMFs with pre-designed lateral offset to construct a sandwich type Mach-Zehnder interferometer of 243.32 μm in length. Sensing performances of the proposed vector bending sensor is theoretically analyzed in detail. As the applied curvature increases from 0.3873 m-1 to 3.0 m-1, the transmission spectra of the proposed sensor show distinct linear wavelength shift sensitivities for different directions, the maximum of which is up to 3.419 nm/m-1. Besides, temperature test indicates that the proposed sensor possesses a low temperature cross sensitivity of 33.71 pm/°C, which ensures its applicability for practical uses in temperature-fluctuated environment. Hence, our proposed vector bending sensor possesses such desirable merits as high sensitivity, compact size, low thermal crosstalk, low cost and orientation-dependent spectral response.