Investigation Of Photonic Crystal All-optical-switch Using Side-coupled Waveguide-cavity Systems

With the rapid development of information technology,all-optical transmission makes the capacity of network gradually increase,however,owing to the optical-electrical conversion in information exchange processing,the exchange rate is difficult to meet the bearer network requirements.Photonic crystal is a kind of artificial microstructure employing periodic distribution of dielectric constants,with characteristics of PhotonicBand-Gap and Localized-State,so that it can bind the transmission path of photons in its internal,furthermore,by means of a variety of nonlinearity,it can complete such as narrowband filtering,optical cross connects and other information processing action.In this paper,the physical properties of the waveguide and the microcavity are analyzed by combining the basic characteristics of two-dimensional photonic crystal.The research on the all-optical switch of side-coupled system is the focus of this paper.Such structure has the advantages of high extinction ratio and small exchange granularity.It is an ideal unit of all-optical array.The main contents of this paper can be summarized as follows:First of all,we briefly introduced the basic structure of photonic crystals,PhotonicBand-Gap and localized-State characteristics,and today's more mature preparation process,moreover,a comprehensive analysis of the ways to achieve various optical switch has been accomplished.Secondly,combined with the electromagnetic theory of photonic crystal,the three core elements of Finite-Difference Time-Domain: difference scheme,stability of solution value and boundary absorption condition have been discussed.Then,we studied the PhotonicBand-Gap characteristics of two-dimensional photonic crystal,the guided mode optimization method,the resonance frequency and the system spectral characteristics corresponding to two different coupling patterns between waveguide and microcavity.In the side-coupled structure,owing to the mismatch between the waveguide and the air interface pattern,the waveguide equal to a F-P cavity,so that the interaction between the equivalent F-P microcavity and the side-coupled resonant microcavity is like to that of the Fano resonance,then the response spectrum appears symmetry breaking.In the Fourth chapter,we studied the physical mechanism to form this asymmetry,and deduced the numerical formula suitable for spectrum analysis of such system.Theoretical prediction datum and simulation experiments are in good agreement,which further supports the rationality of the research ideas in this paper.Bistable all-optical switch has been widely researched in the academia of basic exchange unit.Switching energy and response latency are its core performance parameters,so in the next chapter we studied the critical condition of pump power and time under the circumstance of applying external pump light.The result shows that when the single-frequency continuous wave is used as the control light,corresponding to various energy degree of signal light,the switching action is completed only when the power of control light satisfies a certain critical condition.However,in the premise that the power of signal light is constant,with the increase of excitation light source power,the required pump time is gradually reduced,and these two values are roughly inversely proportional.This conclusion can be well applied to guide the optimization of side-coupled all-optical switch performance.