Hot-Wire Anemometer Using Cobalt-Doped Fiber-Based Mach-Zehnder Interferometer

A hot-wire anemometer by using a two-arm optical fiber Mach-Zehnder interferometer (MZI) is proposed. A 5mm-long cobalt-doped fiber (CDF) is inserted in the sensing arm of the MZI and optically heated to a high temperature over the environmental by using a 1480 nm heating laser. The interference fringe of the CDF-based MZI shifts with airflow velocity due to cooling effect of the airflow. Airflow velocity is therefore measured by detecting wavelength shift of the interference fringe. In experimental measurement, high sensitivity of -2.1 nm/(m/s) is achieved at airflow velocity of 0.1 m/s and the measurement range is 0-2.0 m/s. The CDF-based MZI hot-wire anemometer possesses several advantages including high sensitivity, simple structure, easy fabrication and low cost.