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Research On Key Technology Of Fiber Resonator And Resonator Fiber Optic Gyroscope

Posted on:2007-10-31Degree:DoctorType:Dissertation
Country:ChinaCandidate:Q YaoFull Text:PDF
GTID:1118360215470490Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Optic resonator is a kind of multiple-beam interferometer, which is extremely sensitive to optical wavelength and resonator parameters. Based on Sagnac effect, ring resonators made by fiber can be used to measure the relative rotation angular velocity of objects to inertial space, which become a new type of fiber optic gyroscope—resonator fiber optic gyroscope (R-FOG).The precondition to use fiber resonator to measure rotation angular velocity is to acquire high performance and stable resonance, which requires the overcome of polarization instability of fiber resonators and extremely narrow line width, tunable, high coherent light source. The technique of narrow line-width light source and polarization-maintaining fiber devices in our country is in low-level for long term, which blocked the deeper experimental research on fiber resonators. In this paper, on the base of the technical breakthrough on highly coherent tunable laser and polarization-maintaining device, the experimental study on fiber resonators has been preceded. A stable fiber resonance device has been established, and the polarization-maintaining fiber resonator for medium precision R-FOG application has been obtained.To use fiber resonator for high-sensitivity signal detection, some signal modulation and closed-loop frequency control on resonator must be made. In this paper, the square-wave signal modulation method using digital phase ramp and the closed-loop frequency control methods based on laser frequency modulation and phase ramp frequency offset have been studied in detail. The effects of digital system quantizing error and kinds of phase modulation error have been analyzed. Based on the establishment of high-performance fiber resonator, the experimental investigation on square-wave signal modulation and closed-loop frequency control on fiber resonator has been made. Using digital phase ramp and laser frequency modulation, we realized the all-digital closed-loop signal processing and frequency control on fiber resonator, which gives the basis of further experimental researches on R-FOGIn general fiber optic gyroscopes, there are PZT or optical waveguide phase modulator for signal modulation. These modulators are all connected with electronic circuits, which limit the application of FOG in some special mal-conditions. The fiber resonator studied in this paper, which using digital signal modulation and closed-loop control, has no electronic devices in sensitive ring, and can be connected to other parts of the system with long-range fiber in remote distance, which provides a possible way for long distance, all-fiber, passive rotation detection based on fiber network.The main innovations and creative points in the dissertation were as follows:1. The relation between resonant characteristics of fiber resonator and characteristics of laser and coupler was analyzed. And also the influences of polarization crosstalk of the fiber coupler and polarization-axis misalignment of the splice on the polarization performance were studied in detail. Finally, based on the research results, we obtained the important theoretical evidence for developing high-performance polarization-maintaining fiber resonator.2. We theoteytically analyzed the effects of kinds of modulation errors in digital phase ramp on the output characteristics of fiber resonator in the first time, which is verified by the experimental results. We studied the influence of these errors on the performance of square-wave signal modulation. And based on the actual output signal waveform, we designed the digital signal demodulation system.3. The closed-loop frequency control methods using laser frequency modulation and digital phase ramp frequency offset were studied. Based on the two kinds of frequency control methods, we proposed a new kind of R-FOG system based on long-range fiber network, which provides a possible way for long distance, all-fiber, and passive rotation measurement.4. We developed a practical polarization-maintaining fiber resonator, and have obtained the first stable resonance waveform with 47.8 finesse and 0.38 resonant depth in our country. The fiber resonator also has good polarization performance, and can satisfy the requirements of medium-precision R-FOG5. We completed the experimental researches on square-wave signal modulation and closed-loop frequency control of fiber resonator, realized all-digital closed-loop signal processing for fiber resonator, and have gained 4.32Hz frequency control stability, which will give the basis of further experimental researches on R-FOG...
Keywords/Search Tags:fiber resonator, resonator fiber optic gyroscope, digital phase ramp, square-wave signal modulation, close-loop frequency control
PDF Full Text Request
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