Metamaterial Design Of High-q Optical Magnetic Resonance And Its Second-order Nonlinearity

Metamaterials are artificial composite materials with various physical properties which are nonexistent naturally.Metamaterials can be used in 'perfect lens' and 'invisible cloak' by manipulating electromagnetic wave.In recent years,different kinds of metamaterial arise.For example,negative refractive index metamaterials,chiral metamaterials and optical magnetic metamaterials(An artificial metal nanostructure in which current loops and optical magnetic response can be induced).High Quality factor can be achieved in this kind of structure.It has a good prospect for the application to the biological molecules and gas detection.However,due to the variety of optical nonlinear theories,the development of the nonlinear metamaterials encounters obstacle.But the urgent demands of developing nonlinear metamaterial basic research and realizing all-optical devices require the deep research into nonlinear metamaterials.In this thesis,we design a SRR-rod composite structure and a triple-disk metamaterial firstly.And then we study their optical properties such as surface plasmon resonances and optical second harmonic generation(SHG).This thesis is divided into five chapters:The first chapter introduces the meaning and history of metamaterials briefly.Then,the research progress,realization and applications of nonlinear metamaterials are emphasized.The second chapter describes surface plasmon resonances.Meanwhile,electromagnetic response of two kinds of metamaterial are simulated.First,we design a SRR-rod metamaterial,realizing dual-resonance with a magnetic resonance at 1500 nm and an electric resonance at 750 nm.Then this metamaterial is fabricated and measured.Second,Optical toroidal resonance at visible wavelength of 765 nm in a triple-disk metamaterial is realized by numerical simulation,and the toroidal resonance is identified theoretically by multipolar scattering formulas.The third chapter begins with an introduction to the fabrication and measurement of the triple-disk metamaterial.Then,we describe the fabrication process of the sample as well as the setup details of measurements.Moreover,the measured SEM figure,spectrum and SHG signal of our triple-disk metamaterial are presented.The forth chapter shows the simulation results of SHG signal based on triple-disk metamaterial.The SHG signal is found in the triple-disk metamaterial with DAST as the centeral disk.The results show SHG signal can be enhanced obviously by toroidal resonance in metamaterial.Meanwhile,the Q-factor calculation indicates that the toroidal resonance surpasses magnetic dipolar and high-order resonances,reaching a value of 45 while the Q-factor of magnetic dipolar and high-order resonance are 37 and 12,respectively.Finally,the influences of different geometrical parameters on SHG are studied.The fifth chapter makes a summary and forecast to the research work of this thesis.