A study on the improvement of sensitivity consistency in Sagnac photoacoustic sensing system

Fiber optic acoustic sensing system based on Sagnac interference is widely used in the field of perimeter security. However, the sensitivity of acoustic response varies drastically with frequency, which has become a bottleneck limiting the development of Sagnac photoacoustic sensing technology. An elastic structure is proposed to improve the sensitivity consistency of the photoacoustic sensing system based on Sagnac interference at different frequencies. The elastic structure of optical fiber pickup was optimized by finite element analysis, Solidworks and Comsol. Simulation results show that the designed titanium alloy-based elastomeric structure with a diameter of 110 mm, a height of 100 mm, and an elastomer wall thickness of 3 mm has significantly improved the consistency of the sensitivity of the acoustic response at different frequencies. This work provides a possibility for the application scenario expansion of photoacoustic sensing system based on Sagnac interference.