Patent ID: 8295657

Claim:
An optical fiber sensor, which is provided in a fuel tank of a vehicle, and which detects a property of fuel in the fuel tank, the optical fiber sensor comprising: an optical fiber comprising: a core that comprises a grating that generates a clad mode upon receipt of light; a clad that covers the core; and a fiber jacket that covers the clad, wherein a part of the fiber jacket corresponding to an area where the grating is formed is removed so that the clad is contactable with the fuel; a light source portion comprising a light cutting element that emits light, whose wavelength is within a wavelength band of the cladding mode toward the optical fiber; and a light receiving portion that detects intensity of the light transmitted through the grating, wherein the optical fiber, the light receiving portion and the light source portion are arranged linearly, and wherein at least one of the light source portion and the light receiving portion are immersed in the fuel.