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Design Of Two-Dimensional Photonic Crystal With A Large Complete Band Gap

Posted on:2004-03-07Degree:DoctorType:Dissertation
Country:ChinaCandidate:S S FengFull Text:PDF
GTID:1100360092485951Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
ABSRTACTIn recent years there has been a fast development in the research of photonic crystals, and much work has done both theoretically and experimentally. Photonic crystals have the properties of photonic band gaps and photonic localization, and many potential applications in communications can be expected. To find a photonic crystal structure with a larger absolute gap is still one of the research directions in this field.We introduced two new types of 2D photonic crystal structures formed by an anisotropic material (Tellurium e =23.04, e e=38.44) and air. We have calculated and analyzed the band properties using a FDTD method. For the first structure, the complete two-dimensional band gap of our optimal design reaches A to =0.05 to e (to e=2irc/a, a is the lattice constant, c is the light velocity) at the mid-frequency(tomid) of 0.448 toe, A to /tomid=11.2 %, for wide of veins b=0.01a and rods with radius R=0.2468a. For another structure, the complete band gap of our optimal design is A co = 0.064 coe at co ^=0.475 co e, A to/tomid=13.5%,for wide of veins b=0.012a, side of square s=0.4068a. These band gaps are much larger than those that have been reported for photonic crystals of anisotropic materials. Our numerical analysis also shows that the complete band gap of the structure is quite stably under the perturbation of these structural parameters.Much numerical computed work is required in order to analyze photonic crystals. Therefore, to find a fast computing method is one of the important research directions for photonic crystal studies. In the present thesis, we have considered a 2D photonic crystal of square lattice formed by two materials of dielectric constants. We consider the structure to be formed by a large number of small rectangle or square pixels of uniform size. A revised plane-wave expansion method for quickly calculating the band structure of a photonic crystal of pixel type is used to design a photonic crystal of square lattice with a large absolute band gap at high frequencies. After some band structure analysis with the fast method, some interesting results arefound for a 2D photonic crystal formed by a rectangular lattice of dielectric material GaAs (e =11.4) and air. The optimal structure has a large absolute band gap A co = 0.0514 co e at co nud = 1.4838 co e, A co/tOmid=3.5%. If the photonic crystal is a squarelattice, the optimal structure has a large absolute band gap A co = 0.0995 &e at co mid= 1.2625 co e , A co/comid=8 % . If the photonic crystal is a triangular lattice, the optimal structure has a large absolute band gap A co = 0.1364 co e at co mid= 1.0444 co e, Aco/comid =13.1 %. A fast and efficient plane-wave expansion method has been used for a 2D dielectric photonic crystal formed by large dielectric pixels. This efficient method has been used to find photonic crystals with large absolute band gaps.A numerical method based on the finite-difference time-domain (FDTD) scheme for computing defect modes in a two-dimensional photonic crystal is also presented. Multi-modes and some scattering waves are found. However, single mode resonance can be realized by selecting suitable parameters.
Keywords/Search Tags:2D photonic crystal, complete band gap, FDTD method, revised plane-wave expansion method, pixel type, GaAs, anisotropic material, defect mode, stability.
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