Design And Holographic Fabrication Of Graded Photonic Crystal Lens

Photonic crystal(PC)is an artificial micro-nano structure material discovered in the 1980 s.It is called photonic semiconductor.It is the most promising material for photonic integration and photonic chips.It is widely used in optical communication and optical Sensing and other fields.Graded photonic crystal(GPC)is a new type of PC structure developed in 2005.It has a graded refractive index distribution and can greatly expand the application field of PC.The optical lens based on the GPC structure has excellent characteristics such as nano-focusing,large transmission bandwidth,and small aberration.These characteristics greatly enrich and expand the PC's ability to manipulate and control photons,and it will simplify and improve the performance of optical links in the future.Significance.In this paper,the multi-beam double cone interference method is used to design and fabricate the GPC structure,the GPC structure is adjusted by adjusting the beam performance parameters,and the flat lens is designed based on the obtained GPC structure to study the focusing characteristics of the lens.The main research contents of this article are as follows:1.Introduced the research status and trends of gradient photonic crystals,as well as the research progress of GPC in optical waveguides,optical absorbers and other applications,especially focusing lens applications.2.Introduce laser holographic interference theory,lens focusing and Fourier transform,effective medium theory,provide a theoretical basis for the subsequent design and focusing characteristics of GPC lens structure;briefly introduce the finite element analysis method to carry out the GPC lens pair Simulation analysis of the focusing characteristics of the incident beam.3.Constructed a multi-beam double-cone interference theory model.By changing the model parameters and the optical characteristics of the beam,a GPC structure array was designed,that is,a double-period GPC structure with gradual light intensity distribution.Based on the laser holographic interference theory,the beam characteristics such as internal and external cone beam angles,beam intensity and polarization characteristics were changed,and the influence of beam characteristics on the lattice period,filling rate and lattice edge structure of the GPC structure was studied;Interfering with the number of beams,GPC structures with different lattice structures are designed.In the experiment,the double-cone interference experimental device was built using the two-parameter topless prism independently developed by the laboratory,and the GPC structure was initially observed with a micro camera system.4.Based on the light intensity distribution in the designed GPC structure,the Fourier transform method is used to study its focusing characteristics,and the GPC lens is constructed in the Comsol software,and the light field propagation and focusing characteristics of the simulated lens are simulated by the finite element method.The light intensity distribution of the designed GPC structure is used as the transmission function of the lens to perform Fourier transform,thereby observing the light intensity distribution on the focal plane of the lens and obtaining the focusing characteristics of the lens.Based on the light intensity distribution in the designed GPC structure,the GPC lens structure with gradient of polymer dielectric column size is designed and constructed in Comsol software,and the light field propagation and focusing characteristics of the lens are studied by the finite element method.The simulation results show that the GPC structure lens has a good focusing effect.