Multimodal Speckle-polarization Fiber-optic Sensing for Localized and High-bandwidth Vibration Monitoring

High-bandwidth and multi-point acoustic and vibration sensing is a critical asset for real-time condition monitoring, maintenance, and surveillance applications. In the case of large scales and harsh environments, optical fiber distributed sensing has emerged as a compelling alternative to electronic transducers, featuring lower installation and maintenance costs, along with compact footprints and enhanced robustness. Yet, current distributed fiber-optic sensing solutions are typically costly and face a resolution-bandwidth tradeoff. In this work, we present an alternative fiber-optic vibration sensing strategy that harnesses a multimodal architecture combining speckle and polarization interrogation. The experimental results demonstrate the concept by achieving speckle-based signal source localization with centimeter-range spatial resolution, while obtaining a high-fidelity waveform reconstruction over at least 100 Hz-40 kHz bandwidth via the polarimetric sensing part. Overall, the work establishes a general and promising blueprint to harness multimodality in fiber sensing and break single-modality constraints.