Wavelength multiplexed Ф-OTDR based on a cross-arranged dual-wavelength UWFBG array

Phase sensitive optical time-domain reflectometry (Φ-OTDR) based on ultra-weak fiber Bragg grating (UWFBG) array measures the dynamic strain by extracting the phase of the reflective signals. However, the performance is challenged by the trade-off between spatial resolution and sensing distance. In this paper, we propose a wavelength division multiplexed (WDM) Φ-OTDR based on a cross-arranged dual-wavelength UWFBG array to overcome this limitation. By combining the vibration positioning results of two wavelengths, high resolution and long sensing distance can be achieved at the same time.