Fabrication Of Photonic Crystals With Photonic Band Gaps In The Visible Range Using Holographic Lithography Method

Photonic crystals are artificial micro-structure materials with photonic band gaps (PBG) which can mold the flow of light.PBG materials,which are regarded as "photonic silicon" in the age of photonic information,are analogy with semiconductor materials "silicon".In recent years,the PBG materials attract a great deal of attentions from physicists and engineers.Now restricted by the micro machining technology, fabrication of mesoscale photonic crystals with large area and high quality,especially with PBG in the visible range,is still a great challenge.At present,it has been reported that photonic crystals were fabricated successfully using the method of holographic lithography,which has been verified to be a good method for fabricating mesoscale structure,in this thesis,the 2D and 3D optical lattices were designed and simulated based on the principle of holographic lithography.Then the 3D photonic crystals with tunable PBG in the visible range were fabricated under the direction of innovative research,which is the optical lattice transformation from 2D to 3D by holographic lithography. The main contents are described as follows.1.Based on the optical lattice,the principle of holographic lithography was discussed.One computer program was written to calculate the intensity distribution of the multi beams interference pattern.The simulation results were shown by DX explorer.2.The 2D periodic and quasi-periodic optical lattices were simulated by the computer program.By changing the beams configuration,the 2D optical lattice surprisingly transforms to 3D structure,which is periodic in the z direction,and the 2D periodic and quasi-periodic symmetry in x-y plane is still kept.The Optical Lattice transformation from 2D to 3D can be easily achieved by theoretical calculations.3 Take noncoplanar ten-beams interference as example,the influences on the optical lattice are discussed by adjusting optical parameter such as beam numbers, schemes,polarizations,and incident angles in the numerical simulation program.The simulation results can instruct directly the experimental research.4.488nm laser,which lasing from argon ion laser,is used to fabricate 3D photonic crystals in photoresist SU-8.The 3D crystals show the quasi-periodic symmetry in x-y plane,but periodic in the z direction by the characterization of SEM. The samples exhibit photonic band gaps in the visible range,and display a simple relation between periodicities,which is in good agreement with numerical simulation results.Layered photonic crystals,which are fabricated by changing polarization angle, agree well with numerical simulation results.