The Research On Coupling Characteristics Between Inner And Surface Photonic Crystal Waveguides

Although the concept of integrated optics has been presented nearly half acentury, the photonic integration is far from the expectation due to the large sizes ofcomponents and low degree of integration. Since1987, the concept of Photoniccrystals(PCs) have been put forward by Yablonovitch and John simultaneously, whichare artificially fabricated periodic dielectric structure, have opened a new way torealize photonic integrated circuits (PICs) due to the ability to control the light-wavein size of wavelength. Photonic crystals (PCs) are a promising platform for therealization of ultra low loss optical transmission due to their ultracompact sizes andother unique properties in controlling the propagation of electromagnetic (EM) waves.As one of the key components to be realized in PICs, coupled structure areintensively investigated. This paper starts with the external and inner of PCs slab, andthen investigating the light-transfer properties of the surface waveguides and innerwaveguides by combine using surface modes.The light transmitting and coupling characteristics of surface-mode-waveguides(SMWs) based on PCs with a square lattice of dielectric cylinder are investigated andsimulated by the Finite Difference Time Domain method. We demonstrate thatsurface waves can be efficiently propagated in the outer space of PCs. This thesisrealizes highly efficient coupling between inner and surface PCWs by modifying thestructures of waveguides and interface. The aim of the modification is to achievegood match of modal field profiles between different types of waveguide structures.In order to further optimize the efficiency of coupling into photonic crystal (PC)inner waveguides (IPCW), this paper use a modified tapered structure at the interfaceto realize highly efficient coupling from surface PCWs into IPCW based on all-PCstructures. The introduction of the modified taper is aimed to compress gradually theextended field propagating at the surface as well as excite the surface mode at themodified oblique surface. Good matching of modal field profiles on the both sides ofthe interface is achieved by keeping the waveguide structures changeless. Thenumerical results based on finite-difference time-domain simulations show that the bandwidth for coupling efficiency is very well.Based on the related experiment conditions, this thesis also explores thefabrication and detects the optical properties of photonic crystal structures.Nanosphere lithography technique is used to fabricate nanostructured arrays. The keyprocess of the technique includes self-assembly of2D arrays of nanometer colloidspheres, plasma etching etching technology, Thermal evaporation technique, wetchemical etching, and so on. Then hexagonal lattice photonic crystals with very goodcyclical and light effect were fabricated.In conclusion, the research on highly efficient coupling characteristics betweendifferent photonic crystals waveguides, and the fabrication of photonic crystalstructures provide a good idea and method to achieve a new superior function ofphotonics device.