| In recent years,metamaterials have attracted special attention due to their application in the field of slow light and laser frequency doubling,so the study of their nonlinear optical properties has become particularly important.The application of metamaterials in the field of slow light is mainly caused by its Electromagnetic Induction Transparency effect.In order to achieve better controllable slow light applications,this paper proposes a new structure to realize dual-band Electromagnetic Induced Transparency(EIT-Like)effect in terahertz spectrum.It can be seen as a grating-like metamaterial composed of multiple U-shaped resonators,and through coupled resonator models and simulation data analysis,the cause of its EIT-Like window can be attributed to the near-field coupling between the bright-bright modes of the two U-shaped resonators.In addition,we can also realize the multi-window EIT-Like effect by adjusting its structural parameters,and there is a large group delay in the transparent window,which is expected to obtain more important potential applications in slow optical transmission and optical storage.The application of metamaterials in the field of laser frequency doubling is mainly caused by its nonlinear optical properties.In this paper,a metamaterial composed of asymmetric double U-shaped resonator elements is proposed,and through the nonlinear coupled resonator extension model and simulation data analysis,we discuss in detail the reasons for the formation of enhanced second harmonics of the metamaterial: the resonant coupling between two U-shaped resonators with different resonance frequencies enhances the second harmonic generated by one of the U-shaped resonators.Moreover,the nonlinear coupled resonator extension model proposed in this paper can extend the resonator of the model by considering the number of resonators in the metamaterial unit,so this method can be used to analyze the nonlinear phenomenon of metamaterials with complex metamaterial structures. |
