| Integrated optic gyro(IOG)is a new type optical angular velocity sensors which plays an important role in inertial navigation systems.It is designed on the basis of integrated optics and fabricated by using micro-nano processing technology to realize the integration of various optical devices.The advantages of high precision,large dynamic range and chip-scale integration make it one of the most promising optical rotation sensors in the field of inertial technology.As an integrated optical sensor,the IOG can be made of various materials include inorganic optical waveguide materials such as silicon,silica,lithium niobate,semiconductor and organic optical waveguide materials.Compared with inorganic materials,polymeric optical materials have the merits of strong nonlinear effects,molecular design for high performance and flexible preparation processes.Studies with polymer materials and devices have always been hotspots in the field of integrated optics.Especially with the emergence of surface plasmon polaritons(SPPs),the advantages of polymer materials including flexible preparation techniques and strong nonlinear effects have been fully utilized,which also pushed the integration level of integrated optics from microscale to nanoscale.Therefore,the researches on polymer IOG have important exploration significance and high practical value for realizing fully integrated,low-cost,low-power and high-performance IOG.In this thesis,we aimed to study the design method and fabrication process of the centimeterscale polymer optical waveguide ring resonator with high Q factor and its application in resonant integrated optic gyro(RIOG).By using low loss polymeric optical materials and high performance electro-optic polymer materials with flexible fabrication process,a chip-scale RIOG was realized.Based on the RIOG,the Sagnac effect of the polymer optical waveguide ring resonator was firstly verified,which provided theoretical guidance and technical supports for developing low-cost,high-performance IOG in the future.In addition,we also explored the potential applications of long-range SPP(LRSPP)waveguide in IOG.This thesis began with the review of IOG including research backgrounds,development,materials and fabrication techniques.Then,we showed our research works on the design,fabrication and performance testing of the polymer RIOG.The major achievements of the thesis are list as follows,1.We theoretically studied the basic principle of optic gyro.Based on the theory of Sagnac effect in vacuum and medium,we obtained the expression of resonant frequency difference of resonant optic gyro.In order to analyze the transmission characteristics of the two kinds optical ring resonator,the transfer functions were derived according to the multibeam interference theory.For system design of the RIOG,we established the relationship between the shot noise limited sensitivity and the characteristic parameters of the resonator.We also introduced the operation principle of the resonant optic gyro.Based on the phase modulation technique,the mathematical model of the demodulated signal was built,which provided theoretical guidance for the design and fabrication of the polymer optical waveguide ring resonator and the verification of Sagnac effect.2.We developed a centimeter scale low-loss polymer optical waveguide ring resonator for the application of RIOG.Firstly,we designed and fabricated a single-mode polymer optical waveguide with a low propagation loss of 0.118 d B/cm.Based on the results,we designed and optimized the curved waveguide and directional coupler in the optical waveguide ring resonator.Then,a polymer optical waveguide ring resonator with a high quality factor up to 6×105 was fabricated,which can be served as the key sensing unit for RIOG.Lastly,an open-loop RIOG system was constructed,and the bidirectional resonance curve of the resonator were observed.On the basis of measured results,we theoretically analyzed the open-loop output characteristics,which laid a firm foundation for the rotation test of the gyro.3.We designed and fabricated a Y-branch electro-optic modulator using polymer electrooptic materials for the needs of closed-loop RIOG.Firstly,we synthesized disperse red 1 doped fluorinated polyimide(DR1/FPI)and side chain polyurethane-imide(PUI)electro-optic materials,and measured its refractive index and electro-optic coefficient.A high electro-optic coefficient of 56.31 pm/V was acquired with side chain PUI.Then,the Y-branch optical waveguide was carefully designed including the optimization of the cross-sectional structure of the inverted-ridge waveguide and the branch angle of the Y-branch.By using spin-coating and wet-etching process,the Y-branch electro-optic modulator was fabricated.A low half-wave voltage of 1.875 V was acquired with PUI polymer Y-branch electro-optic modulator.The successfully fabricated low half-wave voltage polymer electro-optic modulator can be served as a key device for the closed-loop RIOG.4.Based on the results of polymer optical waveguide ring resonator and polymer Y-branch electro-optic modulator,we further fabricated a chip-scale polymer RIOG and realized the verification of its Sagnac effect.Firstly,a polymer RIOG which includes a polymer optical waveguide beam splitter,an electro-optic phase modulator and an optical waveguide ring resonator was fabricated.A higher quality factor up to 9.49×105 was acquired.Then,we designed a proportional-integral(PI)feedback circuit and built a closed-loop RIOG system.The Sagnac effect of the polymer optical waveguide ring resonator was verified through the rotation test,which laid a technical foundation for the development of high-precision polymer IOG in the future.5.We explored the potential applications of SPP waveguides in IOG.Firstly,we theoretically studied the fundamentals of surface plasmon.Then,we designed a polymer LRSPP waveguide with optimized structure.The fabricated LRSPP waveguide exhibits a low propagation loss of 1.92 d B/cm at 1550 nm.By employing the LRSPP waveguide,we constructed a single polarization hybrid fiber ring resonator.The measured results show that only TM polarized component can pass through the LRSPP waveguide and resonate in the resonator.The unique feature of single polarization was expected to solve the problem of polarization noise in the optic gyro.Lastly,we proposed and developed a flexible tunable optical attenuator based on LRSPP waveguide which provided new research ideas and techniques for realizing tunable ring resonator without polarization noise in the future.Studies on exploring applications of SPP in IOG are of great significance for expanding the application fields of surface plasmons and promoting the development of optical inertial technology. |
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