High accuracy temperature and strain measurements with cm spatial resolution for distributed Brillouin-based fiber optic sensors

摘要

By combining a DC and a short pulse (～1 ns) laser as the probe beam in the pump-probe configuration of Brillouin-based fiber optic sensors, we have developed a new two-stage method to achieve both high accuracy strain/temperature measurement and spatial resolution (order of cm ). Brillouin profile of such a configuration has a two-fold structure consisting of a Lorentzian- and a Gaussian- like portions. Lorentzian-like portion, although gathering information from all over the fiber, has localized and position-dependent information that can be extracted and employed in a signal processing method for high accuracy and resolution measurements. Level of DC to pulse power affects both the position-dependent information of the Lorentzian peak and its SNR relative to Gaussian peak. An optimum level of DC to pulse power for best SNR and position detection capability is discussed.