Temperature compensated fiber optic anemometer based on graphene-coated elliptical core micro-fiber Bragg grating

The ambient temperature fluctuation is a long-standing challenge for the hot wire anemometer due to the strong cross-talk. Here, a graphene-coated elliptical core micro-fiber Bragg grating has been proposed for the detection of flow rate with the temperature compensation. With the strong interaction between the graphene layers and the heating light, the graphene coat on the surface of the microfiber can be heated, acting as a heater. The flow rate can be measured through the different responses of two orthogonal polarization modes to the refractive index change of the graphene layer induced by the heat transfer. More importantly, due to the identical response of two polarization modes to the ambient temperature, the fiber-optic anemometer could compensate the temperature cross-talk effectively. The experimental results show that the sensitivity of the 0.42 nm/(m/s) for the fiber anemometer can be achieved, and the temperature standard variation is only 0.084 nm with the range from 20°C to 50°C. The proposed fiber-optic anemometer is very attractive in the fields of various industries for the temperature self-compensation detection of gas flow.