Analysis Of Multi-channel Tunable Filter Characteristic Based On The Photonic Crystal With Double Defect States

The infrared communication is a kind of modes of communication which put infraredlight as the transmission medium. And it has a lot of advantages, for example a largecapacity of communication, strong confidentiality, good performance on resistingelectromagnetic interference, and so on. The photonic crystal can be used to make avariety of optical devices. Especially on the optical wavelength division multiplexing inoptical communication system, it can increase the transmission capacity of the opticalcommunication system as well as a hundredfold. Therefore, the research aboutmultichannel tunable photonic crystal filter gets more and more people’s attention.It can be made into multichannel tunable filter with good performance using thecharacteristics of the photonic crystal band gap and the photonic crystal defect model,while combining the photonic crystal the coupled-mode theory. And then it can improvethe transmission rate of optical communication system and increase the transmissioncapacity. This paper expands the theoretical derivation, numerical simulation and theanalysis of the characteristics around the photonic crystal with double defect states, andthe main contents include the following aspects:Firstly, starting from the Maxwell’s equations, the generating mechanism of dualdefect modes of one-dimensional photonic crystal with the antisymmetric layer has beenanalyzed using the tight-binding method and the coupled-mode theory. The mathematicalrelationship between the center distance of two defect layers and the frequency of twodefect modes has been set up. And the situation that the center distance of two defect layerinfluences the two defect modes has been simulated. Therefore, the basic structure ofphotonic crystal defect unit has be obtained in this paper.Secondly, the transmission properties of the periodic photonic crystal and defect typephotonic crystals has been studied based on the electromagnetic field theory and using thetransfer matrix method. The effects that mesoscopic calender effect make to defect modeshave been discussed and the relation between the position of defect modes and the strainproduced by applied stress has been got. The structural parameters of photonic crystal and the property of defect models have been analyzed deeply. And the overall structure ofthe photonic crystal has be received for the production of multichannel tunable filter.Finally, the filtering characteristic of tunable filter has been analyzed and comparedwhen the antisymmetric layer of the photonic crystal is different material on thefoundation of the proposed multi-channel filter structure of photonic crystal with doubledefect states. The more reasonable material of antisymmetric layer has been chosen, andthe tunable filter characteristic has been analyzed for the designed photonic crystal usingthe mesoscopic calender effect. So the tunability of this multichannel filter has beenverified.