Fabrication And Characterization Of Photonic Crystal/Quasicrystal And Optical Waveguide Using Optical Induction Method

Photonic crystal is a new type of optical material which is characterized in that the refractive index of the material is periodically distributed.It can manipulate the photon motion just like the semiconductor material manipulates the electron motion.It provides a very promising prospect for the all-optical information system in the future.Therefore,it is very important to study the fabrication technology of photonic crystal/ quasicrystal.Traditional photonic crystal fabrication technologies such as precision machining,layer by layer superposition,self-assembly of micro-sphere structure,laser direct writing have their own limitations: expensive experimental equipment,harsh experimental conditions,high requirements for experimental materials,low preparation efficiency and so on.The study of a method for preparing photonic crystals with lower cost,simpler process and higher efficiency is of great significance for studying the photonic crystal microstructure.Therefore,photonic crystal microstructures fabricated by optical induction method have attracted much attention in academia in recent years.The optical induction method mainly utilizes the photorefractive index change characteristics of photorefractive materials,forms a spatially distributed light intensity pattern,and then irradiates the pattern onto the photorefractive material.After a series of physical processes,photonic microstructures will be formed in photorefractive materials.Materials such as iron-doped lithium niobate crystals also have excellent erasable properties,which can be used repeatedly and save cost.Therefore,the photonic crystal microstructures fabricated by optical induction method have the advantages of low cost,simple experimental setup and flexibility.At present,the method of fabricating three-dimensional photonic crystals/quasicrystals by optical induction method is mainly to produce multi-beam interference through spatial light modulator.The experimental equipment is expensive and the area of three-dimensional photonic crystals is limited by the reflector of spatial light modulator,so it is difficult to apply on a large scale.Optical waveguide is a kind of optical guide components,whose function is to limit light to its interior and let light travel inside it.With the development of optical information technology,the traditional optical waveguide fabrication technology cannot meet the development needs of optical communication technology in the new era.So the scientific community proposed laser direct writing optical waveguide technology in the last century,but most of the current laser direct writing technology uses femtosecond laser,which has the disadvantages of expensive equipment,difficult to optimize experimental setup,and complicated experimental steps.Using the photorefractive effect of photorefractive materials,optical waveguides can also be fabricated by optical induction method.The experimental equipment is inexpensive,the experimental materials are simple and easy to obtain,and the experimental setup optimization is also simpler.Aiming at the problems existing in the fabrication of three-dimensional photonic microstructures and optical waveguides,based on optical induction technology,the fabrication of three-dimensional photonic crystals,three-dimensional photonic quasicrystals and optical waveguides in iron-doped lithium niobate crystals has been studied in this paper.The main innovations are as follows:(1)Three-dimensional photonic crystals and three-dimensional photonic quasicrystals can be fabricated simply and efficiently by means of a multi-wedge prism with a central hole.By this method,the cross-sectional area of three-dimensional photonic microstructures can be simply expanded,and the types of three-dimensional photonic microstructures can be varied.(2)Proposed an experiment and an algorithm that compresses a large scale image which is too large or difficult to be photographed to be observed directly in experiment into a limited observation space by using multi-plane reconstruction technology.(3)Quantitative analysis of three-dimensional photonic crystals fabricated by a three-wedge prism with a central hole shows that the structure of the three-dimensional photonic crystals is not simply the addition of a third dimension to the twodimensional structure.Its cross section perpendicular to the central optical axis is nested by three sets of interlaced lattices.(4)A method of adjusting the period of threedimensional photonic crystal/quasicrystal by changing the angle of wedge angle to change the deflection angle of multi-beam is proposed by combining experiment with theory.(5)Ring waveguides are fabricated by optical induction method using Bessel beams generated by phase-only spatial light modulators,which proves the feasibility of fabricating optical waveguides by optical induction method.