High-sensitivity, low-noise, and stable fiber vibration sensor using an integrated fiber cantilever beam with surface plasmon resonance microcavities.

Fiber-optic vibration sensors have been studied widely owing to their anti-electromagnetic interference, corrosion resistance, and ease of integration and distribution. Previous reports primarily focused on the frequency detection of vibration signals. However, the amplitude sensitivity, noise-equivalent amplitude (NEA), and stability determine the sensing precision and accuracy of the device. The present work proposes a fiber-optic device for detecting vibration signals. A fiber cantilever beam in-line structure is integrated on the surface of the surface plasmon resonance (SPR) microcavity at the end facet of a single-mode fiber (SMF). The device can detect broadband vibration signals (1-150 kHz) under the experimental conditions in the study. The amplitude sensitivity of the device reaches 396.64 mV/µm at 100 kHz with a signal-to-noise ratio (SNR) of 61.5 dB at 0.41µm, and the NEA of the device is as low as 2.97 pm/Hz with good linearity in frequency detection. In the absence of any feedback control system, the device has a low standard deviation of 2.15% in response to vibration signals, limited by the stability of our optical testing system. The developed device is a perfect combination of fiber configuration, miniaturization, high sensitivity, and stability, making it a promising candidate for detecting vibration signals in the future.