Tunable Novel Multi-channel Filters Based On Ring Resonators

Recent years,the fiber communication system which is capable of high-speed transmission cause more and more attention for people's endless quest for communication speed.The WDM(Wavelength Division Multiplexing)technique is the core part within the system.Ring resonator become the new hot to realize WDM for its flexibility,compactness and tenability.As for the fundamental structure of ring resonator,add-drop resonator could be cascaded or parallel coupled to achieve multichannel filter.However,the complexity of the structure and the difficulty in controlling are increasing during the process.Thus,in this paper,a novel configuration is proposed to solve the problem to some extent.Firstly,the development and the change of ring resonator are reviewed,we mainly analyse the progress of add-drop resonator and the application in multichannel filter.In addition,we summarize and ayalyse the current research status to point out the problem.Secondly,the basic theory of ring resonator is briefly introduced which starts from the all-pass single ring resonator.Furthermore,the spectrum is analysed via mathematic methods.We also research on the basic structure of add-drop resonator,the method of calculation and the characteristic of spectrum,besides,the phase change,the high sensitivity and dispersion characteristics of resonance point are discussed.Then,a novel add-drop interferometer configuration is introduced,we propose the alternative structure with the analysis of optical path,and present a method for the sort of add-drop resonator's calculation.The output spectra are simulated with MATLAB,and the reason for the two kinds of spectra is discussed with regulation method introduced.In addition,a peculiar appearance is found and we make an experiment to approve it.Finally,we design a structure for the dual-channel filter,the calculation for the output equation and the output spectra via simulation are presented.The bandwidth,the extinction ratio and the reconfiguration of passband are tuned by the coupling coefficient,the attenuation factor and the phase difference correspondingly.We also prepare two experiments to prove the dual-channel result.One for the reconfiguration of the channels and the other for the controlling of the bandwidth.The number of channels can be extended by the cascading of add-drop interferometers,and we finally obtain the four channel filter which exhibits the result similar with the comb filter.The reconfiguration is also realized via controlling the phase difference in the four channel filter.