Electromagnetically Induced Transparency In All-Dielectric Silicon Metamaterials

Electromagnetically induced transparency(EIT)is a quantum interference phenomenon in the three-level atomic system,which is caused by the quantum destructive interference between different transition pathways.It can produce a narrow transmission window,so that light can propagate freely through an initially optically opaque medium.Previous studies on electromagnetically induced transparency have mostly focused on gas media,however,this requires stringent experimental conditions such as high-intensity laser and cryogenic temperature.Electromagnetically induced transparency of plasma metal metamaterials cannot avoid ohmic loss.These adverse conditions can be avoided in electromagnetically induced transparency based on all-dielectric metamaterials.Therefore,the electromagnetically induced transparency effect based on low-loss all-dielectric silicon metamaterials has attracted much attention.Electromagnetically induced transparency effect has many excellent characteristics such as high transmission and strong dispersion,so it has important applications in slow-light devices,storage of quantum information,optical sensors and nonlinear optics.In this dissertation,the finite-difference time-domain(FDTD)method is used to simulate the electromagnetically induced transparency effect based on all-dielectric silicon metamaterials.The main work is as follows:(1)A U-shaped metamaterial structure with periodic array consisting of three silicon nanorods is proposed.One horizontal nanoscale bar serves as a bright mode resonator and two vertical nanoscale bars act as a dark mode resonator.The quantum destructive interference between the two resonators leads to electromagnetically induced transparency with the transmittance of 92% and the Q-factor of 130.By changing the period size of unit structure,polarization angle of incident light and refractive index of surrounding medium to explore the variation of electromagnetically induced transparency window.A nanoscale metamaterial refractive index sensor with sensitivity of 203 nm/RIU and FOM of 29 has been obtained.The optical delay of 0.75 ps is obtained by analyzing the phase change of transmission window,which shows the application potentiality in slow-light devices.(2)Furthermore,a ?-shaped metamaterial structure is proposed to achieve electromagnetically induced transparency,and the Q-factor of 2436 is obtained.The variation of electromagnetically induced transparency window is explored by changing the period size of unit structure and refractive index of surrounding medium.The influence of the gap between bright mode resonator and dark mode resonator on the electromagnetically induced transparency effect is studied theoretically.At the same time,field enhancement can be achieved by designing and adjusting the gap between the two resonators.The sensitivity of the designed metamaterial structure to surrounding medium is 184 nm/RIU,and FOM is 460,which can be applied to optical sensing,surface enhanced spectroscopy and so on.