Design,Fabrication And Electromagnetic Wave Control Of Dielectric Metamaterials

Metamarials are composed of artificial “atoms” periodically or disorderly.The size of artificial “atoms” is much bigger than that of natural atoms.It helps us to control its properties freely.We can design artificial materials with abnormal electromagnetic properties by modulating the shape,size and property parameters of artificial “atoms”,the artificial materials may not exist in nature.Utilizing metamaterials to realize absorber and optical swiching has aroused wide attention due to its significant application.However,so far most of the absorber metamaterials and optical switching metamaterials are based on metal structure artificial “atoms”.Actually,the Mie resonances of dielectric metamaterials provide a new way to build metamaterials.It may further improve the performance of absorber and optical switching devices.This article is focused on studying single band,dual-band and wide band absorbers and optical switchings with low switching energy and high switching speed based on dielectric metamaterials.We design and fabricate a single band absorber based on ferroelectric metamaterials.Its absorptivity is 99% at 8.96 GHz.Both the permittivity and permeability spectra of this metamaterial have resonance around 8.96 GHz,and the value of permittivity is approximately equal to that of the permeability at 8.96 GHz,resulting in the impedance of the metamaterial to be 1.The impedance match condition has been satisfied.Therefore,we achieve near 100% absorptivity.The absorption band is insensitive to the polarization and inci dent angles of the electromagnetic waves.The absorption band will shift to higher frequency when we decrease the size or permittivity of the artificial “atoms”.We have studied dual-band metamaterial absorbers based on different cube size and different permittivity of ferroelectric artificial “atoms”,and dual-band metamaterial absorbers based on two Mie resonances.All these three dual-band metamaterial absorbers have two absorption bands with near 100% absorptivity.Also,both two absorption bands are insensitive to the polarization and incident angles of the electromagnetic waves.The frequency and intensity of the absorption bands can be tuned separately or simultaneously by modulating the size and property parameters of artificial “atoms”.We have studied wide band metamaterial absorbers based on ferroelectric artificial “atoms” with gradient size and permittivity,and wide band metamaterial absorber based on the coupling of higher order Mie resonances.All these th ree absorbers achieved wide band absorption,and the width of the band can be modulated artificially.We design an all-optical switching device based on the thermal effect of Mie resonances of ferroelectric metamaterials.The signal wave can be swith from “close” state to “open” state by modulating the intensity of control wave.Controlling electromagnetic wave by another electromagnetic wave with different frequency can be realized.We also design all-optical switching devices based on modes transform of metal structure and dielectric metamaterials.The speed of modes transform in metal structure and dielectric metamaterials is equal to the speed of light.Therefore,we have achieved ultrafast response of all-optical switching.The working frequency of the all-optical switching can be tuned by modulating the size and property parameters of artificial “atoms” in metal and dielectric metamaterials.