简介:Weintroduceanewmodelofone-dimensional(1D)photoniccrystalcomposedofalternatelyarrangedRHMandLHMlayerswithpositiveandnegativerefractiveindicesrespectively,forwhichthetransmissionspectraofthemodelarecalculatednumericallywiththetransfermatrixmethod,andtheband-gapstructureandthepolarizationpropertiesareanalyzed.Wefoundthattheintroductionofnegativerefractiveindexlayers(i.e.LHMmediumlayers)givesrisetosomepeculiarband-gapstructureandpolarizationpropertiesasfollows.Firstly,theforbiddenbandsareextremelywideandthetransmissionbandsareverysharpwithoutoscillation;andsecondly,thechangeofincidentanglehasdifferentinfluencesontheforbiddenbandsofTEandTMmodes.FortheTMmode,theforbiddenbandwidthdecreasessubstantiallyandfinallyvanishes,andfortheTEmodewithcentralwavelength,thetotalreflectionhappensatanyincidentangle.
简介:Thereflectivityofone-dimensionalchalcogenidephotoniccrystal(CGPC)structurewiththefirstorderreflectionbandinnearinfrared(NIR)regionistheoreticallystudied.Sb-SeandGe-Schalcogenideglassesareusedashighandlowrefractiveindexlayersrespectively,becausethesematerialshavezeroabsorptioninNIRregion.Thetransfermatrixmethod(TMM)isemployedtocalculatethereflectivespectraoftheproposedstructure.ThetheoreticalresultsofreflectivespectraofbulkchalcogenidematerialswiththecompositionofSb40Se60andGe30S70for4,8,12and15layersandthicknessesof117nmand183nmrespectively,atnormalincidence,arecloseagreementwiththeexperimentalresults.Furthermore,byincreasingthenumberoflayersofSb40Se60andGe30S70,thereflectionbandscanbeenhancedinthewiderrangeoftheNIRregionforthepolarizationatdifferentanglesandthusthebroadbandomnidirectionalreflectorcanbedesigned.
简介:一个简单二节的极化模式分散(PMD)赔偿者为多信道的PMD赔偿被建议,它能补偿二或甚至更多的隧道同时。因为统计特征和PMD的频率依赖,为有中等PMD的当前的单个模式纤维,所有隧道严重地同时被降级的概率是极其小的,它使补偿稠密的波长部门multiplexing(DWDM)可能有用这个赔偿者的中等PMD的传播系统。它被显示出停止概率一40?????$