| Surface plasmon is generated by the interaction between electromagnetic waves and conductive electrons on the surface of conductive materials.Due to its confinement of deep subwavelength mode and strong near-field enhancement,it can be applied to imaging,biosensors,negative-refractive materials,etc.However,in a lower frequency range,the behavior of conductive metal is regarded as an ideal conductor,and the internal field is zero.At this point,the energy of the incident light cannot be transmitted inside the metal or on the surface,and the surface plasmon oscillation cannot be generated.The emergence of spoof surface plasmons can effectively solve the above barriers,effectively extend its working frequency band to the microwave and terahertz fields,and provide more application value for functional devices and optical integrated circuit systems in this frequency band.In this paper,the chain waveguides of spoof surface plasmons with angular bending transmission are designed based on the ultra-thin square spiral metal structures,and the transmission characteristics of the chain are studied.In terms of subwavelength surface plasmon devices and optical integrated circuit systems,the chain waveguides are more flexible and occupy a smaller area.The main research contents are as follows:(1)Two types of square spiral metal structures with smaller size and lower frequency band are designed,based on which the transmission characteristics of the spoof surface plasmons are studied.Firstly,the square spiral structure is designed.Secondly,the resonance characteristics of this structure are studied.Finally,the change of resonance characteristics of the two types of structures is observed by changing the parameters of the structural unit and the dielectric substrate.Through simulation studies,it is found that spoof surface plasmons can be transmitted on the designed two types of structures.(2)Based on the above two types of square spiral structures,the coupled transmission characteristics on two structural units with different arrangements are designed and analyzed.Based on the two types of square spiral structures,the near-field coupling characteristics and transmission spectrum when they are connected together and disconnected from the distribution are studied,and the structural coupling resonance changes are investigated by changing the structural parameters.It is shown that the coupling effect between the dimers is very sensitive to the surrounding environment and has certain application prospects in detection,and it is also shown that spoof surface plasmons can still be transmitted when the rotation angle between this structure is changed.(3)Based on two types of square spiral structures,a chain waveguide structure is designed with different regular arrangements,and the transmission characteristics of the designed waveguide structure are mainly analyzed.The transmission spectra and dispersion relations of translational,rotational and combined chain waveguides are mainly investigated,and it is found that the near-field mode distributions of chain structures with different bending cases are continuous,indicating that the spoof surface plasmons can transmit well even when the adjacent structures are bent to different degrees.(4)Based on the square double spiral structure,a square spiral antenna structure is designed.The analysis of standing wave,gain and directional diagram of this antenna mainly shows that the spoof surface plasmon can be applied to the square double spiral antenna,which extends the research scope of this structure and provides the research value for the development prospect of micro and nano devices. |
