Design And Properties Of Metamaterials Based On The Epsilon-Near-Zero Media

Epsilon-near-zero（ENZ）medium is a kind of material whose real part of permittivity is zero at specific frequency.Owing to the extraordinary optical properties,relatively high tuning flexibility and high compatibility,it has become a hot topic in photonics research.ENZ materials show remarkable electric field enhancement characteristics and ultrafast response at ENZ frequency,and also defects such as incident angle limit and impedance mismatch.Metamaterials are artificial materials whose optical properties depend on specific structural design,and can be designed to achieve extraordinary physical properties.Integrating ENZ medium into metamaterial structures can break the limitation of bare ENZ material.In addition,the coupling effect of two kinds of resonance system can greatly enhance the light-matter interaction,and provide new inspiration for photonics research.In this paper,four hybrid metamaterial structures based on ENZ media are designed,and their excellent optical control properties are studied by using the finite element method.The main content of this paper is as follows:1.A metamaterial system of the nanoantenna composited with ENZ film is designed.Simulations have demonstrated that the plasmon induced transparency like effect（PIT-like）can be realized via the coupling of plasmon resonance mode and ENZ mode.The mechanism of the transparent window is further clarified by electric field analysis.The adjustments of the transparent windows and coupling strength via the structure parameters and the AZO film thickness are further investigated.2.A metamaterial structure composed of dolmen structure and ENZ film was designed to realize double transparent window.The physical mechanism of the double transparent window is illustrated by simulation.One transparent window originates from the plasmon induced transparency effect supported by the dolmen structure,and the other is induced by the PIT-like transparency effect via the coupling of plasmon resonance and ENZ modes.The tuning effects of structure parameters and ENZ film thickness on double transparent windows were further studied.3.A composite metamaterial structure was designed to place ENZ film into a classical three-layer metal-insulator-metal（MIM）absorber to achieve tunable near-perfect broadband absorption and double-band absorption.The broadband absorption was achieved due to the plasmon resonance mode and the ENZ mode on the edge of strong coupling via optimizing the parameters.By increasing the thickness of the dielectric layer,the coupling of the plasmon resonance mode and the ENZ mode becomes weak resulting in the dual-bands absorption.The tuning effect of carrier concentration and damping factor of ENZ film on the absorption peak was further studied.4.A multilayer stacked metamaterial structure of ENZ dielectric layer and SiO₂ dielectric layer is designed.The unpatterned nearly perfect wideband absorber was achieved since the multiple local resonance modes between layers enhance the light absorption,and the ENZ resonance further increases the light loss.Further theoretical simulations show that the absorption band can be tuned by adjusting the filling fraction and the carrier concentration of ITO film.