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5 March 1993 Brillouin fiber optic gyro with push-pull phase modulator and synthetic heterodyne detection
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Proceedings Volume 1795, Fiber Optic and Laser Sensors X; (1993)
Event: Fibers '92, 1992, Boston, MA, United States
Intracavity phase modulation in a fiber-optic ring laser gyro can provide 'optical dithering' to reduce the effects of frequency locking while retaining optical reciprocity in the cavity. We show that the use of two antiphased phase modulators placed symmetrically within the fiber cavity can provide uniformly distributed dithering. A modulation index of 2.4 theoretically eliminates the zero-order lock-in band around zero frequency, while use of a high modulation frequency puts higher-order lock-in bands outside the beat frequency dynamic range. Push-pull modulation allows for high modulation frequency with minimum dynamic perturbation of the cavity resonant behavior. We describe results with an experimental Brillouin fiber optic gyro operating at 1.3-micron wavelength using push-pull modulation together with a novel synthetic heterodyne detection scheme for sensing rotation rate and direction. A ten-fold reduction of the width of the zero-order lock-in band is observed. We also demonstrate that the observed frequency bias at zero rotation rate is caused by the Kerr effect due to the power imbalance between the two oppositely directed circulating lasers.
© (1993) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Shang Yuan Huang, Keiichiro Toyama, P.-A. Nicati, Luc Thevenaz, Byoung Yoon Kim, and H. John Shaw "Brillouin fiber optic gyro with push-pull phase modulator and synthetic heterodyne detection", Proc. SPIE 1795, Fiber Optic and Laser Sensors X, (5 March 1993);

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