Research On Dispersion Characteristics And Applications Of Optical Ring Resonator

Optical ring resonator has become an important optical device module because of its wavelength selectivity,local optical power enhancement,flexible structure design and compact structure.Common optical ring resonator structures include macro fiber ring,knotted fiber ring,whispering gallery microspheres,etc.Different structures correspond to different application fields: macro fiber ring can be used as the coil of fiber optic gyroscope for rotation sensing.WGM mode microcavity can be used for biochemical sensing and excitation of nonlinear effects due to its small mode volume.Silicon cavity on photonic chip can be used in optical devices such as optical communication and computing because of its small size and stable structure.Aiming at the problems that the dispersion of ring resonator is greatly affected by loss,the measurement dead zone of resonator fiber optic gyroscope exists at high speed,and the parameter design of optical wavelength division multiplexing device is lack of system theory,this paper carries out systematic study on dispersion control based on ring resonator and the application in field of optical communication devices and fiber optic gyroscopes from the aspects of theory and experiment.The specific contents are as follows:Firstly,the physical mechanism of material dispersion and the transmission characteristics of optical ring resonator are described.By introducing the KramersKronig relation,it is proved that the material dispersion is caused by the absorption of the medium to the light field.The transmission characteristics of single ring resonator,add-drop ring-resonator and add-drop ring-resonator Mach-Zehnder interferometer are studied through the transfer matrix method.Secondly,the assisted ring is introduced to regulate the dispersion characteristics of the through and drop port of the add-drop ring-resonator.When the assisted ring is in under-coupled regime,the fast and slow optical characteristics of the two output ports will be reversed.Without changing the coupling state between the base ring and the bus waveguide,the group delay of the two ports can be improved by reducing the loss or increasing the size of the assisted ring,so as to realize the free regulation of the dispersion characteristics.Thirdly,an angular velocity sensing model based on the single ring resonator is proposed to prove the relationship between sensing sensitivity and group refractive index.In order to solve the problem of no signal response of resonator fiber optic gyroscope at high speed,a composite fiber optic gyroscope composed of Sagnac loop and resonant loop is proposed.On the one hand,this composite structure overcomes the defect of low sensitivity of interferometric fiber optic gyroscope at low speed and improves the measurement limit;On the other hand,it solves the problem that the resonator fiber optic gyroscope has no response in the high-speed region.Then,the parameter optimization model and multi-level cascade rule of the optical interleaver based on the add-drop ring-resonator Mach-Zehnder interferometer are studied.On the one hand,a theoretical model based on quantitative dispersion value is proposed to evaluate the influence of loss and transmission coefficient on the flatness of interleaver,so as to optimize the parameters of optical interleaver and greatly reduce the complexity of parameter design;On the other hand,the method of introducing phase shift is proposed to quantitatively summarize the cascade rule of multi-level interleavers,so as to obtain the wavelength division multiplexer with dense channels.Finally,two new optical interleavers based on the resonator structure are proposed.One is the switchable optical comb filter/interleaver structure based on the ring resonator.By adjusting the tunable coupler,the filter can switch between the two functions,so as to reduce the system complexity of the multiplexer.Second,the thirdorder reflective hybrid interleaver based on fabry-perot cavity assisted michelson interferometer improves the order of the interleaver without increasing the complexity of the device,so as to obtain better filtering effect.These two new interleavers are beneficial to further improve the integration and miniaturization of wavelength division multiplexing.The research work of this paper begins of the theoretical derivation,studies the theory of fast and slow optical inversion,improves the inherent defects of the resonator fiber optic gyroscopes,and studies the role of dispersion in the parameter optimization of optical filter.Meanwhile,combined with actual needs,the wavelength division multiplexing devices conducive to integration and miniaturization are designed.It provides a reference for the further development of ring resonators in the fields of optical communication,fiber optic gyroscope and fast and slow light.