Photonic Bandgap And Localization In Photonic Crystals Composed Of Different Materials

Photonic crystals(PCs)are a kind of artificial periodic structures composed of different materials.The PCs include photonic bandgap(PBG)and photonic localization so that they can control the propagation of electromagnetic waves in the specific wavelength range or at some wavelength.If the defects are inserted within the PCs,defect modes will appear in the PBG so that the filtering phenomena can be realized.The optical properties of PCs depend on the effective modulation of the PBG and photonic localization.However,once PCs have been fabricated,it is usually difficult to modulate their optical properties.In optics and photonics,ion beams have been successfully applied to modulate the optical properties of materials so that it is possible to modulate the optical properties of post-fabrication PCs based on ion beam technology.In recent years,the interactions of electromagnetic waves with metamaterials have attracted much attention since metamaterials have the unique electromagnetic properties.If the PCs are composed of metamaterials and conventional materials,it is found that they usually have the unique capability to manipulate the propagation of electromagnetic waves.Therefore,it is important to study the properties of PCs containing the metamaterials.This dissertation include two main theoretical and experimental researches.The first section mainly introduces efficient modulation of PBG and defect modes in PCs by energetic ion beams.The other section introduces omnidirectional photonic bandgap in PCs containing hyperbolic metamaterials.In chapter 2,the PBG and photonic localization in photonic crystals are effectively modulated by energetic ion beams owing to the induced modification of the thicknesses and refractive indices of the materials.In this section,we investigate theoretically and experimentally the modulation of the PBG and defect modes of one-dimensional all-dielectric photonic crystals by using carbon ion irradiation.It has been found that the PBG and defect mode have a remarkable hypsochromic shift when the photonic crystals are irradiated with carbon ions.The degree of the blueshift mainly depends on the reduction of the material thickness that is nearly proportional to the fluences of carbon ions.The blueshift of the band edges and defect modes shows a step-like behavior from transparency to opacification(near-zero transmittance or high reflectance)or a converse trend.Our work paves a new way to tailor the photonic crystals towards the development of novel devices with tunable specific wavelengths and wavebands.In chapter 3,we investigate theoretically and experimentally the omnidirectional PBG in PCs composed of hyperbolic metamaterials and conventional dielectric materials,where the hyperbolic metamaterials are the subwavelength metal-dielectric periodic multilayers.It is found that the long-wavelength edge of the PBG has a unusual red shift with the increase of the incident angle but the short-wavelength edge has a converse trend for the TM polarization.The experimental results are in good agreement with the simulation values.Such PCs containing the hyperbolic metamaterials can be used to fabricate novel optical devices including high-Q omnidirectional reflectors.