The application relates to a wind turbine component having an optical fiber sensor arranged to detect wind speed over the surface of the component. In one embodiment, the optical fiber sensor has a light loss portion that allows some of the light transmitted through the optical fiber to escape. The amount that the optical fiber bends in the air flow across the surface causes the effective surface area of the light loss portion to increase or decrease. With increased or decreased surface area of the light loss portion, more or less light is lost from the fiber. The intensity of the light transmitted in the fiber can therefore be used as a measure of the amount of bending, and therefore as a measure of the air flow's speed. In other embodiments, the optical fiber includes optical gratings, such as Fiber Bragg Gratings.