Vector Bending Sensor Based on Hole-Assisted Three-Core Fiber Mach-Zehnder Interferometer

A vector bending sensor based on hole-assisted three-core fiber (HATCF) Mach-Zehnder interferometer (MZI) is demonstrated. The sensor is composed of multi-mode fiber (MMF) - HATCF - MMF structure embedded between two single-mode fibers (SMFs). The bending curvature and direction can be identified by interrogating the wavelength of the interference peak, and the maximum bending sensitivity of −28.726 nm/ $\text{m}^{-1}$ is obtained at the 220° direction. In addition, the sensor has a temperature sensitivity of 44 pm/°C and is insensitive to the external refractive index (RI).