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Optical Absorptance And Nonlinearity Optical Properties Of One-dimensional Photonic Crystals Containing Loss Materials

Posted on:2019-04-21Degree:MasterType:Thesis
Country:ChinaCandidate:J LiFull Text:PDF
GTID:2371330542997187Subject:Physics
Abstract/Summary:PDF Full Text Request
The concept of photonic crystals was first proposed in 1987 and has attracted wide attention.Since the lattice constant of photonic crystals is comparable to the wavelength of the electromagnetic wave length,multiple Bragg scattering plays the important role to control the propagation of the electromagnetic wave.One typical characteristic of photonic crystals is that they have the photonic band gap which is similar to the electric band gap to control the movement of electrons in semiconductors.If the defect layer is inserted in photonic crystals,the defect mode will appear in the photonic band gap.The electromagnetic wave of the defect mode can tunnel the whole structures.In the defect of photonic crystals,the electromagnetic fields are enhanced by photonic barriers in both sides of the defect.Therefore,if lossy materials is inserted in the defect,the light of defect mode can be absorbed intensively.Optical nonlinearity is a kind of optical phenomena dependent on field intensity.Enhanced intensity of electromagnetic fields can decrease the threshold of the optical nonlinear effect.Optical Tamm States(OTSs)are the electromagnetic surface States which are formed near the interface of metal and truncated photonic crystal.The electromagnetic fields of OTSs are mainly localized near the interface,while the intensity is exponentially attenuated when it is far away from the interface.However,the metal is easily oxidized in the general environment to change or fail the performance of the devices since the dielectric constant of the metal is easily changed.Therefore,it is significant that non-metal materials are selected to replace metal.Transparent conductive oxides(TCOs),including indium tin oxide(ITO),aluminum zinc oxide(AZO),gallium zinc oxide(GZO),etc.,are ideal substitutes for metals in the infrared region.The dielectric constant curves of TCOs are similar to those of metals in the infrared range.Moreover,they are stable in the general environment.In addition,the material parameters of TCOs can be adjusted by changing the doping ratios and experimental conditions,and their losses can be much smaller than those of the metals in the infrared region.Therefore,the TCO is a kind of good materials to realize OTSs in the infrared range.In the second chapter,we theoretically and experimentally study the optical properties of one-dimensional defective photonic crystals where the graphene is inserted the center of the defect layer.The light wave of a particular frequency has a strong localized electromagnetic fields in the defect,where the electric field intensity in the defect can be changed by adjusting the structures of photonic crystals.We designed two structures including symmetric and asymmetric defective photonic crystals,and the graphene is in the center of the defect.The optical absorption of the defect frequency can be increased greatly.Otherwise,we can adjust the local electric field intensity of the defect frequency by increasing or decreasing the number of period number of photonic crystals,and obtain the relationship of the local electric field intensity and the absorptance.In the third chapter,we mainly study the enhanced nonlinear optical effect of photonic crystals containing the graphene.According to two different photonic crystals containing graphene and the relationship between local electric field intensities of defect frequencies and the absorptance in the second chapter,the relationship between the threshold of optical bistability and the local electric field intensity is investigated detailedly.In this chapter,the conditions to achieve the minimum threshold of optical bistability is summarized in the photonic crystals containing the graphene.It has important scientific significance to develop new nonlinear optical devices.In the fourth chapter,the optical Tamm state in the photonic heterostructures with transparent conductive oxides is studied experimentally.This chapter focuses on the optical parameters of transparent conductive oxides which is similar to those of metals in the infrared region,and the heterostructures are composed of thick transparent conductive oxide film and all-dielectric photonic crystal.In this chapter,we use three kinds of transparent conductive oxide(ITO,AZO,GZO)instead of metals,and the optical Tamm state is observed experimentally in three different heterostructures.
Keywords/Search Tags:Photonic crystal, Nonlinearity effect, Optical tamm state, Graphene, transparent conductive oxide
PDF Full Text Request
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