Abstract: Disclosed is an optical fiber gyroscope comprising a fiber coil composed of a lengthy optical fiber wound therearound in a predetermined number of turns, a coupler for optically coupling an optical fiber led from a light source and an optical fiber led to a photodetector, and an optical IC chip arranged between the fiber coil and the coupler and provided with a phase modulator and a polarizer mounted on an optical waveguide, the optical fiber gyroscope further comprising a fiber coil reel around which the lengthy optical fiber for constructing the fiber coil is wound in the predetermined number of turns, a coupler reel around which the optical fibers led in both directions from the coupler are wound in a predetermined number of turns, and a housing member including a plurality of compartments (reel-placing region, frame, frame) for accommodating at least the both reels, the light source, and the optical IC chip.

Abstract: In an optical fiber gyro for detecting a rotation angular velocity by Sagnac phase difference of light signals propagated through an optical fiber sensing loop, no polarizer is used, and a light source having a difference in attenuation or amplification factor between two orthogonally polarized lights is used. Alternatively, a light source is optically coupled to an optical coupler for supplying two divided light signals to the sensing loop and receiving the two light signals propagated through sensing loop by an optical fiber of a predetermined length which is set to meet a relation in which a distance difference determined by the predetermined length and a phase difference of two orthogonally polarized lights propagated through the optical fiber is greater than an interference distance of the light source.