Fiber-Optic Anemometer Based on Distributed Bragg Reflector Fiber Laser Technology

We present a novel fiber-optic anemometer based on a distributed Bragg reflector (DBR) fiber laser. The anemometer consists of a fiber laser pressure sensing element and a Venturi tube designed to convert the wind velocity into differential gas pressure that can be measured by the fiber-laser sensor. A DBR fiber laser that has two polarization modes is designed and fabricated as the major sensing element in this anemometer. The fiber-laser sensor is demodulated by the beat frequency of the two polarization modes, which has higher sensitivity and lower cost over wavelength-demodulated fiber-laser sensors. The experimental results show that the sensor's response to wind velocity is quadratic in the measurement range of 8 ~ 40 m/s, the short term repeatability is better than 0.5%, and its sensitivity is impacted by the power of pump laser. Additionally, this anemometer has the potential capability to be used as a flow meter for both gas and liquid flows.