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

A low-cost and highly compact fiber-optic 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 ?m 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 temperaturefluctuated 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.