Improving Sensing Performance of Plate-Type Fiber-Optic Accelerometers Using Noncircular Fiber-Optic Coils

The commonly used mandrel-type or disk-type fiber-optic accelerometers (DT-FOAs) are inherently limited in their capacity to detect low-frequency signals due to their structural characteristics. The fiber-optic coil (FOC), as the core sensing component of an interferometric FOA, plays a crucial role in determining the sensor’s sensitivity through its strain distribution characteristics on the transducer plate. This article presents, for the first time, the novel introduction of noncircular FOCs (NC-FOCs), which are employed in the design of a rectangular thin-plate FOA and plate-tpye FOA (PT-FOA) to improve low-frequency detection performance. In this study, the finite element method (FEM) and tensor analysis theory are employed to establish a universal model for PT-FOA constructed with NC-FOCs. Sensors with FOCs of various shapes were designed, fabricated, and tested. Both theoretical and experimental results demonstrate that different shapes of FOCs can improve sensitivity by approximately 14.62%. The underlying mechanisms of these improvements are analyzed by studying the strain tensor distribution on the transducer plate. The proposed PT-FOA addresses the limitations of existing FOAs in low-frequency detection. The sensitivity enhancement method maintains the same resonant frequency and thermal noise levels while significantly improving the signal-to-noise ratio (SNR) and sensitivity of the sensor. This work provides a general modeling approach and valuable practical guidance for the design and optimization of high-sensitivity FOAs, with important implications for both research and application.