Passive Resonator Fiber Optic Gyro Composed of Waveguide/Fiber-optic Devices with Schemes to Reduce Noises

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The purpose of this research is to develop a pasive resonator fiber optic gyro using waveguide-type or fiber-optic-type devices, and study the ways to include the countermeasures against several noise factors in the system. It is desirable to compose all the system with guided-wave devices for achieving stable operation of the gyro. The following research results have been obtained.[1] We have invented the new system configuration named "Digital serrodyne resonator fiber optic gyro, " in this study, in which the input optical frequency into the resonator is controlled by waveguide-type optical phase modulators with the driving waveform of sawtooth-shape having digital staircase slope. This waveform is easily generated by using an A/D converter. Using the gyro chip, which is an integrated optical waveguide devices on LiNbO3 substrate especially designed for interferometer fiber optic gyros, the experimental setup has been constructed. Rotation detection has been successfully demonstrate … More d by this setup.[2] The driving waveform has been shown to be generated by the digital logic. A/D and D/A converters with about 12 bits is enough for achieving 7 digits of the dynamic range, which is required for aircraft navigation. Is has also been shown that the backscattering induced noise and the optical Kerr effect induced drift can be reduced only by modifying the driving waveform for the phase modulators. The ways to reduce the drirt due to the poralization fluctuation and the Faraday effect through the earth magnetism have already been implemented into the system.[3] The resonators composed of twisted ordinaly single mode fiber have been made, which are stable from the view point of the poralization fluctuation. Experiments have confermed the stability.[4] Active resonator fiber optic gyros, utilizing the laser oscillation in the fiber ring resonator, have also been studied. Experimental setup of the Brillouin fiber optic gyro has been constructed, by which the rotation detection has been carried out successfully. Less