Researches On Photonic Crystals Waveguide By Using Transformation Optics

In recent years, Electromagnetic Metamaterial (EM) is a new conceptin the field ofelectromagnetism. EM has received much attention because of its unique electromagnetic response.Transformation Optics (TO) is proposed as a new design method in EM. TOis based on coordinatetransformation theory. By transforming the space coordinate,we can control the propagation ofwaves.Photonic Crystal (PC) is a kind of EM, PChas created a new cross-cutting areas of condensedmatter physics and optics, laying the foundation for the development of new photonic devices.Ourpaper has combined TO and PCs in designing waveguide devices by using the Photonic Band Gap(PBG) and photonic localization. Based on it, the electromagnetic waves in waveguide can propagatewithout losses and band-pass or band-stop characteristics.In the first part, we will use the method of TO to design several waveguide shifters which canrealize low losses at the corner. The angle of the corner β will be-90°<β<90°. At the same time, wehave improved the devices by embeddingPCs in it. By using this method the waveguide shifter mayhave band-stop characteristics.In the second part of this article, the angle of the waveguideconnector can be±90°without losses.Compared with the conventional rectangular waveguide connector, this connector can minimize thelosses at the corner. Base on the method, a new type of waveguide connector can be designed. Thesize of waveguide connector can be set up, so that it can connect two waveguide of different widths.We replace the common waveguide connector byPCs waveguide connector. By using the properties ofPBG and defect states, the waveguide connector may have band-pass function and get bettertransmission characteristicsIn the third part, we have designed a kind of right angle waveguide splitter. Compared withconventional splitters, the new splitters can split a bunch of incident beam into two beamswithoutlosses. On the basis of the method,another PCs splitter is designed. By using the characteristics ofPBG and photonic localization, the splitters can have band-pass filter characteristics and better outputwaveform. By changing the filling factor and the ratio of medium, the effects on band-passcharacteristics of splitters have been studied.