Cascadable 2-D Vector Accelerometer Based on Differential Sensitivity Enhancement in Internal Seven-Core Fiber

Vector vibration measurements have received increasing concern due to their great practical application. We present a novel 2-D vector accelerometer that uses a seven-core fiber (SCF)-inscribed Bragg grating for miniature and highly integrated 2-D vector sensing. Combining the fiber with a novel metallic capillary cantilever beam structure improves the accelerometer’s natural frequency and enables stable multistage multiplexing. By studying the difference in wavelength shifts of the edge-core Bragg gratings, both a substantial sensitivity increasement and temperature self-compensation of the accelerometer are realized. Experimental results indicate that the accelerometer has a natural frequency of 98 Hz, an acceleration sensitivity of 723.9 pm/g in the operating frequency range, and a minimum detectable acceleration of 8.1 mg, which is much higher than that of the existing similar accelerometers. Furthermore, this accelerometer can identify the 2-D vibration acceleration information perpendicular to the 0°–360° direction in the plane of the fiber. Owing to its excellent performance of high sensitivity, high integration, small size, cascade multiplexing, and immunity to temperature, the accelerometer has potential applications for detection in narrow high-temperature spaces, such as oil and gas exploration wells.