Fabrication And Optical Property Study Of(2+1)D Photonic Crystal Structure

Photonic crystals are artificial periodic dielectric materials with the characteristic of photonic bandgap(PBG).The existence of PBG enables them to control the behavior of photons in a similar manner as what semiconductors do for electrons.Photonic crystal materials have great application prospects in the field of optoelectronic area.(2+1)D photonic crystals,as a novel photonic crystal structure,possess unique advantages in both structural tunability and optical property compared with traditional 1D,2D and 3D photonic crystals.However,the structure of current fabricated(2+1)D photonic crystals is not so perfect.Structural imperfection is still a big challenge,which greatly limits the systematic study on its optical property and structure-property relationship.Furthermore,fine regulation of band gap structure has not yet been achieved.This thesis focused on the controllable fabrication of high-quality(2+1)D photonic crystals and study on their basic light transmission properties as well as photonic bandgap engineering.The main contents and results are summarised as follows:1.Preparation and characterizaton of high quality,high mechanical strength colloidal crystal monolayer(CCM),which is the basic building block of(2+1)D photonic crystal structure.First,we adopted the air-water interface self-assembly and solvent vapor annealing method to prepare high-quality CCMs.The in situ annealing effectively decreased the defects introduced during transfer and dry process,and improved the mechanical strength of the CCMs.Second,the mechanical strength of CCMs with different annealing time was quantitativly characterized for the first time by AFM nano-imprint technology.Such high-quality and self-supported CCMs laid a foundation for bottom-up fabrication of highly ordered(2+1)D photonic crystals.2.Fabrication of(2+1)D photonic crystals with enhanced crystalline integrity and study on their basic optical properties.Based on the high-quality and high-mechanical-strength CCMs,(2+1)D photonic crystals with enhanced crystalline integrity were successfully fabricated by a layer-by-layer technique.We studied the impact of surface property of the substrate,the solvent annealing time,and PS spheres' size on structure and optical property of(2+1)D photonic crystals.In a(2+1)D photonic crystal,it was found that PBG position ?c ? 2.528 D and interplanar distance d ? 0.912 D,where D is the diameter of PS sphere.Furthermore,PBG broadening,enhancement and angle independence were observed in(2+1)D photonic crystals.Taking advantage of these unique optical properties,the Ga N-based LED with a matched(2+1)D photonic crystal back reflection mirror demonstrated an enhancement of 94%(@350 m A)in light output power compared with a traditional LED.3."PBG engineering" in a(2+1)D photonic crystal.By changing the CCM's sphere size and stacking order,flexible control in structure and stop band position of the(2+1)D photonic crystal superlattice and heterostructure have been realized.The influence of the sphere size of the two monolayer building blocks on the optical properties of the(2+1)D photonic crystals superlattice has been investigated.The superlattice structure exhibits fine control in PBG position and obvious PBG resonance enhancement.The relationship between the PBG structure of a(2+1)D photonic crystals heterostructure and the two component(2+1)D photonic crystals was also established.Ultra-wide band gap or multiple photonic band gap heterostructures can be flexibly designed and fabricated.These findings in(2+1)D photonic crystal superlattice and heterostructure lay a solid foundation for tuning the band gap structure of a(2+1)D photonic crystal.