Study On The Field Enhancement Effect Of Terahertz Metamaterials Based On Nanostructures

Terahertz technology has a wide range of applications,among which the study of terahertz field enhancement effect is also one of the research hotspots,often used in the research of nonlinear metamaterial modulable devices,sensors and so on.Due to the process limitations of micromachining,most of the devices in the field of terahertz are micron and submicron structures,so researchers mostly use micron-level or submicron-level in slits or crescent-shaped structures for terahertz field enhancement analysis,but the effect of field enhancement has not been significantly improved.Based on the above,this paper analyzes the electric field enhancement effect of nanoscale slits on structures of the split resonant rings(SRRs).The double nanometer split and single nanometer split metasurface structures are designed,and the electric field enhancement effect of the two structures when the slit width is micron and nanoscale is studied respectively,the sensing characteristics are also analyzed.Besides,the advantages and disadvantages of these two metasurface structures with different nanometer split numbers are also compared.Firstly,this paper elaborates the theoretical knowledge applied,and designs a doublenanometer slit-shaped metasurface structure of the metal composed of two SRRs.For the proposed SRR,the control variable method is used to verify the electric field enhancement effect when the opening size changes from the micron to the nanoscale.The simulation results show that the electric field in the slit of the structure with nanoscale gap has a significant enhancement effect on the electric field in the micron-scale gap,indicating that the electric field enhancement effect will increase as the opening width narrows.The field strength of the variable conductivity material filled with the left slit of the double open shape was verified,and it was found that the conduction effect required to achieve the conduction effect when the gap width was on the micron scale required to achieve the conductivity effect was tens or even thousands of times that of the conduction effect when the nanometer magnitude,which shows that the nanoscale slits in the double-open structure have strong field strength and their conductivity is stronger than that of micron-sized slits,which provides a direction for the design of nonlinear devices.In this paper,the metallic part of single-nanometer open metasurface structure composed of SRR and wire is also designed.Similarly,the simulation results show that the mid-field enhancement effect of the single-opening structure enhances with the decrease of the slit.In addition,two structures with different opening magnitudes in the single-open structure were laid with graphene film to analyze their sensing characteristics,and it was found that the nanoscale slit metasurface structure could be directly conducted at the lowfrequency resonance point within the given relaxation time range.It shows that the designed metasurface structure has a strong field strength at the opening when the opening is in the nanometer order and the graphene can directly conduct the low frequency,which can be applied to adjustable sensing.At the end of this paper,the two designed structures are compared and analyzed,and it is found that when the gap width is of the same magnitude,the electric field enhancement effect in the nanoslit of the double-open structure is stronger than that in the nanoslit of the single-open structure.It can be seen that the double-open structure is better for non-linear and sensor devices.