Designing Optimization Algorithm Of Dielectric Antenna For Resonant Broadband Unidirectional Scattering By Genetic Algorithm And The Corresponding Experiment Verification

In the era of big data,the existing optical communication facilities and technologies no longer meet the needs of communication capacity.The huge demand for high speed and broadband communication will stimulate new breakthroughs in various aspects of optical communication system.Dielectric antenna is considered as one of the most promising integrated optical devices because it can realize the artificial regulation of electromagnetic wave in nanoscale and has lower Ohmic heat loss compared with metal antenna.The optical medium antenna can be used not only in the field of communication,but also in the field of photovoltaic solar cells and bio-medicine.However,how to design and optimize the performance of the antenna is always a cumbersome problem for researchers,so it is of great significance to develop a physical mechanism oriented optical antenna design and optimization method combined with evolutionary algorithm.In the characteristics of optical antenna,the unidirectional scattering effect is one of the most important evaluation criterions.In the application,the bandwidth of unidirectional scattering is also one of the important parameters to evaluate its performance.To date,however,the research of resonant broadband unidirectional scattering optical antenna has not been widely developed.According to the Kerker condition,the coupling of electromagnetic dipoles is the physical mechanism of unidirectional scattering,which can be represented by the overlap of electromagnetic dipoles.In this thesis,we propose an optimization scheme of unidirectional scattering optical antenna based on the unidirectional scattering physical mechanism,which is not only applicable to the design of various functional unidirectional electromagnetic wave antennas,but also can be extended to the fields of nonlinear scattering optimization and micro wave antennas.The main achievements of this thesis are:(1)A physical mechanism oriented design scheme is proposed: the optimization scheme of the broadband unidirectional scattering antenna combines the electromagnetic multipole expansion and genetic algorithm.According to the Kerker condition,the optimization objective of the broadband unidirectional scattering antenna is to maximize the resonance coincidence of the electromagnetic dipole.(2)Optimizing the design of optical antenna at the wavelength of optical fiber communication to achieve broadband unidirectional scattering: in order to prove the feasibility of the design of broadband unidirectional scattering antenna,the metal dielectric hybrid antenna is optimized first,where broadband unidirectional scattering optimization can be achieved at the optical fiber communication wavelength.At the same time,we also design and optimize all dielectric cylindrical antennas compatible with semiconductor technology,which can also realize the broadband unidirectional scattering phenomenon of the antenna.(3)In order to verify the correctness of the numerical optimization results in the microwave band experiment: we optimized the alumina cylindrical antenna in the microwave band to achieve broadband unidirectional scattering.According to the optimization results,we have prepared the alumina cylindrical antenna and measured its far-field scattering pattern and scattering spectrum.After comparing the experimental measurement and numerical simulation results,we have verified the correctness of the optimization results of this algorithm.(4)Prospect based on Simulation and experimental results: three kinds of broadband unidirectional scattering antennas designed at the wavelength of optical fiber communication and microwave section can be used as the basic structure of the design and application of broadband electromagnetic scattering devices.