The Design Of High-Q Electromagnetically Induced Transparency Metamaterial Resonator

Electromagnetically Induced Transparency(EIT)originates from the quantum interference effect in atomic three-level system,which has the spectral response of low loss,high transparency,narrow band and strong dispersion.The EIT-like effect based on metamaterials is realized by the coupling of bright-dark mode or bright-bright mode.In recent years,the EIT-like effect has attracted researchers’much attention due to its flexible structure design and rich applications,and various novel EIT-like resonators have been proposed.Among them,high-Q EIT-like resonators have developed rapidly because of their good application prospects and practical value in narrow-band filtering,high-efficiency slow light,high-sensitivity optical sensing and other fields.In this paper,we mainly focus on the realization of the high-Q EIT-like effect and propose two kinds of high-Q EIT-like resonators with different coupling modes.The main research work of this paper is as follows:(1)Based on bright-dark mode coupling,an S-shaped all-dielectric metamaterial that achieves a high-Q EIT-like response is presented.The structure is composed of an S-shaped silicon rod and a quartz substrate.Breaking the symmetry of the S-shaped structure could provide a pathway to excite a dark magnetic mode that coupled to a bright electric dipolar moment,achieving a sharp EIT-like response.And the Q value of the resonance can be easily modified by altering the asymmetric degree of the structure,and the maximum Q value is 3*10~4.Furthermore,the influence of structural parameters on EIT-like resonance are also calculated,and the results show that EIT-like transparency window will shift accordingly as the structural parameters(silicon bar’s length,width,or thickness)change,but the symmetric shape of the EIT-like responses will almost not be affected and the transmission of the EIT-like resonances keeps a stable value of 97%all the time,which is owing to the small detuning between the two interacted modes.However,the detuning of the two interacted modes will become larger than the tolerance as structural parameters change in other EIT-like resonators,making the EIT-like transparency window disappeared or changed into Fano resonance.In addition,the application of the resonator in optical sensing is further analyzed,and the result shows that the high sensitivity of 317nm/RIU can be achieved when its surface is covered with 2um thick sample solution.(2)Based on bright-bright mode coupling,an analogue of electromagnetically induced transparency(EIT)with a high-Q in a stacked metal-dielectric metamaterial(MM)is demonstrated.The stacked MM consists of two layers,a silver frame array that is used as one bright electric resonance,and a silicon rod array served as another bright toroidal mode,based on these two modes,a high-Q EIT-like effect can be achieved.Furthermore,the amplitude and Q value of EIT-like resonance can be adjusted by changing the distance between the upper and lower layers,and the maximum Q value can reach 2.6*10~4,which is much higher than the Q value of EIT-like realized by other resonators based on bright-bright mode.In addition,we also calculate the effect of structural asymmetry on the EIT-like resonance,and the results shows that the resonance position,intensity and Q value of the EIT-like transparency window hardly change when the silicon rod moves 180nm along the horizontal x-axis or 35nm along the vertical y-axis in the case of the position of the upper metal frame is kept unchanged,which will be useful for the designing and engineering of the device.