Highly Compact Vector Bending Sensor With Microfiber-Assisted Mach– Zehnder Interferometer

Abstract

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 $243.32~\mu \text{m}$ in length. Sensing performances of the proposed vector bending sensor are theoretically analyzed in detail. As the applied curvature increases from 0.3873 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.