All-single-mode fiber-optic gyroscope with long-term stability

Abstract

A new all-fiber gyroscope is described. All components are constructed directly on a single continuous optical fiber, removing localized sources of reflection. A laser-diode source is used to reduce coherent scattering effects. Proper choice of modulation frequency is shown to reduce instabilities further. Long-term stability at rest of better than 0.2 masculine/h is observed with 30-sec integration time.

Analysis of Temperature Dependence of Thermally Induced Transient Effect in Interferometric Fiber-optic Gyroscopes

“…The presence of any additional non-reciprocal errors causes overestimation in the analysis because they usually cannot be distinguished from the Shupe effect induced errors. The broad spectrum of the utilized EDFS, about 20 nm, reduces not only the nonreciprocal phase error due to back reflections and backscattering in the Sagnac interferometer [12] effect [13]. The IOC with a high polarization extinction ratio over 60 dB and birefractive PMF with an h-parameter of less than 10 -5 utilized in the fiber coil can suppress the phase error due to the effect of polarization cross-coupling to a considerably lower level [14][15].…”

Fibre-Optic Sagnac Interferometer as Seismograph for Direct Monitoring of Rotational Events

“…This was a very important step in the progress of performance, but it was not enough for an ultimate performance which is obtained only if the unbiased response is perfectly even and the biasing modulation has only odd frequencies. For the above reason, the PM being actually a delay line filter, the operation at the so-called proper or eigen frequency (Bergh et al, 1981) -the delay through the coil is half the period of modulation, suppresses the residual even harmonics which are always present because of spurious nonlinearities of the modulation chain. Today the FOG system using also a broadband source has the intensity statistics that happens to cancel the Kerr effect induced phase difference in a Sagnac interferometer (Ezekiel et al, 1982).…”

New measurement method for eigen frequency of a fiber optic gyroscope

“…Many sources of rate-output errors are reduced or effectively eliminated by operating the bias modulation at the eigen frequency. [4][5][6][7] Establishing an accurate measurement of eigen frequency has been challenging. Existing approaches include the direct measurement methods based on the symmetrical square-wave bias modulation, 8,9 asymmetrical, square-wave bias modulation, 10,11 and techniques based on servo control using an eigen frequency detector.…”