A novel SiO2 optical waveguide resonator for acoustic sensing in complex underwater environments

Purpose This study aims to tackle the issues of signal distortion and performance instability caused by environmental interference when high-sensitivity silicon dioxide optical waveguide resonator acoustic sensors (OWRAS) operate in real-world, complex underwater environments, such as those with turbulence, noise and pressure variations. The core objective is to enhance the sensor’s practical environmental adaptability. Design/methodology/approach A novel protective encapsulation design is introduced, utilizing polyurethane as the sound-transparent material due to its excellent acoustic impedance matching with water. A standardized underwater acoustic testing system was constructed to conduct a comparative performance analysis between the encapsulated sensor and a reference hydrophone. The evaluation comprehensively assessed key operational conditions, including environmental noise, source level detection, turbulent disturbance, dynamic sound source and hydrostatic pressure. Findings The experimental results demonstrate the outstanding performance of the encapsulated sensor. Its noise level is comparable to that of the reference hydrophone, with a high level of consistency in source-level measurements. The sensor maintains stable output under turbulence and dynamic sound sources, matching the reference hydrophone’s trends, with negligible 0.1 dB sensitivity drift after 3 MPa hydrostatic pressure exposure. These results collectively validate its exceptional mechanical stability and environmental robustness. Originality/value The core originality lies in the specialized polyurethane encapsulation structure designed specifically for OWRAS, effectively balancing acoustic transparency with mechanical protection. Through systematic environmental adaptability verification, the high-performance laboratory devices have been advanced one step toward practical engineering applications, providing key technical support and practical evidence for the reliable use of optical underwater acoustic sensors in complex marine environments.