Temperature-Insensitive PCF-Based Low Amplitude Vibration Sensor for Broad Frequency Application

Fiber-based vibration sensors have extensive applications in scientific measurements and industries such as health monitoring, seismic activity tracking, and fluid flow detection. In this work, a photonic crystal fiber-based modal interferometer is fabricated for physical vibration sensing that can operate in high-temperature environments. The interference pattern of the fabricated probe gives periodic wavelength shifts due to external dynamic strain, which is applied using a piezo transducer. The probe is characterized by different vibration amplitudes of 5V, 7.5V, and 10V over a frequency range of 5 Hz to 350 Hz. It shows good sensitivity throughout the characterization frequency range, with a maximum sensitivity of 5.14 pm/10 volt at 10 Hz. The fabricated probe will be useful for low-strength and high-frequency mechanical vibration detection for monitoring physical fields like acoustic, fluid, and terrestrial traffic, to name a few. The thermal stability of the fabricated probe is investigated, and no shift in wavelength is observed for temperature variation between 25°C and 250°C.