• Korean Journal of Optics and Photonics
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• v.13 no.5
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• pp.377-383
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• 2002

An all-digital closed-loop (ADCL) signal processor for an open-loop FOG was developed to replace the analog circuitry of a Digital Phase Tracking (DPT) signal processor with new digital circuitry. When the ADCL signal processor without a stabilizer for fiber phase modulator (FPM) was attached to the FOG, temperature drift of FOG was about 0.26$\mu$rad/$^{\circ}C$, which makes the FOG unusable in medium or higher-grade applications. This drift was due to variations of phase modulation amplitude and phase delay of the FPM. The stabilizer controls its phase modulation amplitude and phase delay by regulating the ratio of harmonics of the FOG output. Thus, the stabilizer reduces the drift of the FOG to negligible.

• Proceedings of the Optical Society of Korea Conference
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• 1996.09a
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• pp.57-57
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• 1996

• Korean Journal of Optics and Photonics
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• v.23 no.5
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• pp.203-210
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• 2012

Sagnac interferometer gyroscopes can be divided into three large generations using starting points of time or highlights of their research. As the first generational Sagnac interferometer, the ring laser gyroscopes have been studied since the 1960s by laser invention, and as the second generational Sagnac interferometer, the fiber optic gyroscopes have been studied since the 1970s by invention of optical fiber for communication. In the latter half of the 1990s, after having confirmed the wave theory of the atom, studies of atomic interferometers were started for a next generation gyroscope application. This paper discusses the operation principles, application, and future prospects of these three generations of Sagnac gyroscopes.

• Journal of the Optical Society of Korea
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• v.15 no.3
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• pp.237-243
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• 2011

Thermal characteristics, such as diffusivity and temperature induced change in the fiber mode index of rotation sensing fiber coil are critical factors which determine the time varying, thermo-optically induced bias drift of interferometric fiber-optic gyroscopes (IFOGs). In this study, temperature dependence of the transient effect is analyzed in terms of the thermal characteristics of the fiber coil at three different temperatures. By applying an analytic model to the measured bias in the experiments, comprehensive thermal factors of the fiber coil could be extracted effectively. The validity of the model was confirmed by the fact that the extracted values are reasonable results in comparison with well known properties of the materials of the fiber coil. Temperature induced changes in the critical factors were confirmed to be essential in compensating the transient effect over a wide temperature range.

• Korean Journal of Optics and Photonics
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• v.10 no.5
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• pp.396-400
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• 1999

In the fiber-optic gyroscope employing a high-power erbium-doped fiber source, the source excess noise was subtracted from the gyro output through a single processing to improve the gyroscope sensitivity. As the result, we obtained the reduction of noise by 13.5 dB (electrical) which was measured from the noise floor spectrum when the gyro was modulated with the depth of 1.8 rad. In addition, the random walk coefficient of the gyro output was reduced by a factor of 4~5.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 1996.04a
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• pp.21-30
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• 1996

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.317-318
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• 2006

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.37 no.8
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• pp.789-797
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• 2009

Gyroscope's deadzone is a region where can not detect the rate even though the actual rotation is applied. This paper analyzed the cause of deadzone by modeling/simulation and introduced pulse dithering method to overcome. From the testing of 3-axis fiber optic gyro system using 900m fiber, it confirmed deadzone could be effectively eliminated by combination of three factors, dither amplitude, dither frequency, and gyro loop gain.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.370-373
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• 2003

Superluminescent diodes(SLDs) are the optimum light sources for application in optical measurement systems such as fiber gyroscopes, optical time domain reflectometers, and to short and medium distance optical communication systems. The broadband characteristics of SLDs reduce Rayleigh backscattering noise, polarization noise, and the bias offset due to the nonlinear Kerr effect in fiber gyro systems. In this paper, in order to suppress lasing oscillation, we introduced a laterally tilted SCH(Separate Confinement Heterostructure)-SLD with a window region. An output power of 11mW has been achieved at 200mA injection current at 25$^{\circ}C$. At 120mA, parallel and perpendicular to the junction were 31$^{\circ}$${\times}$38$^{\circ}$.

• Korean Journal of Optics and Photonics
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• v.14 no.4
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• pp.449-453
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• 2003

In a broadband erbium-doped fiber source for fiber optic gyroscope, a pump-polarization scrambling scheme is used to suppress the polarization dependence of the source mean wavelength. The degree of polarization of the pump is reduced to 1.4% by applying proper modulation depth to the polarization modulator where 10 m-long single-mode fiber is wound on a cylindrical PZT. In the case of using the pump-polarization scrambler as well as the output depolarizer, the mean-wavelength variations due to the random change of polarization are measured to be less than our measurement limit of 5 ppm.