Study Of Slow-light Effect In Microfiber Coil Resonator And Its Application Exploration For Sending Angular Velocity

Slow-light technology is to slow down the group velocity of light. It is one ofthe key technologies faced by the development of the all-optical communication andquantum computing technology. Moreover, the studies of slow-light technology caneffectively promote the development of many science fields, such as optical sensortechnology, nonlinear optics, and quantum optics. At present, miniaturized andintegrated slow-light elements are the urgent needs for the slow-light technologydevelopment. Combining with the scientific research projects taken by our researchgroup, in this dissertation, using the excellent optical and mechanical characteristicof the microfiber, a miniaturized microfiber coil resonator (MCR) slow-light unitwas innovatively proposed. The unit was experimentally fabricated and its slow-lightproperties were tested. Finally, the MCR slow-light unit was implanted in fiberoptical gyroscope (FOG) angular velocity sensor system to improve its angularsensor sensitivity. Main research contents and innovations in the dissertation includethe following several aspects:(1) Low-loss tapered-microfiber fabrication:Theoretically, based on the optical waveguide theory è using thefinite-difference beam propagation method (FD-BPM), the impact of thetapered-microfiber structure parameters (such as the tapered region profile, the waistregion diameter, and the waist region length) on the characteristics of the lightpropagation in the tapered microfiber was analyzed. Finally, the optimized profileparameters for fabricating a tapered microfiber with good optical and mechanicalproperties were proposed.Experimentally, using a microhearter, precise electronic control translationstages, lifting stages, and so on, we set up an experimental system used to fabricate atapered microfiber. By continually optimizing the structure parameters of the systemand the drawing programs, the tapered microfibers with low loss (the minimum tapered loss is0.05dB), high surface smoothness, waist region around1m indiameter, and length up to tens of millimeters can be fabricated. The system hasgood stability and repeatability. This work establishes a good foundation for thesuccessful fabrication of the MCR slow-light unit.(2) Theoretical and experimental research of the MCR slow-light unit:Theoretically, based on the strong structural dispersion property of the MCR,we designed a controllable MCR slow-light unit and established a theoretical modelfor describing its slow-light transmission. It was analyzed that the impact of therelated parameters (such as microfiber diameter, fiber ring diameter, fiber ringnumber, coupling coefficient between rings, loss) on the properties of resonance,dispersion and slow light in the MCR slow-light unit. Based on the establishedtheoretical model, we simulated the MCR slow-light unit properties of resonance,phase and slow light.Experimentally, using precision revolving platforms, precision translationstages, L shape plates and so on, a winding system of the MCR slow-light unit wasestablished and the unit was fabricated. In the fabrication process, a broadband lightsource and an optical spectrum analyzer (OSA) were used to real-time monitor theresonance spectrum and loss variation of the MCR slow light unit. Using a tunablelaser, an electro-optic modulator, a pattern generator, two photo detectors, a highbandwidth oscilloscope, and so on, a slow-light delay test system was established,and the slow-light delay of the MCR slow-light unit was tested. A maximal relativetime delay of30ps was achieved.(3) Research of the MCR slow-light angular sensor unit:It was explored that the MCR slow-light unit was implanted in the FOG angularvelocity sensor system to improve its sensitivity. The theoretical model of the MCRslow-light angular sensor unit was established, and the enhanced mechanism of thesensitivity was analyzed. Based on the simulation and analysis, we find that whenthe MCR slow-light unit is implanted in the FOG angular velocity sensor system, thesensitivity of the system can be effectively enhanced.The research of the miniaturized MCR slow light unit provides a major theoretical and experimental foundation for promoting the development of theminiaturized and integrated slow-light elements. The MCR slow-light unit isimplanted in the FOG angular velocity sensor system to improve its sensitivity,which will provide an important innovative idea for the development of the FOGwith high sensitivity, light weight, and miniaturization.