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The zero-refractive-index metamaterials have excellent electromagnetic properties, which provide new ideas and methods to realize the control of electromagnetic waves and the design of new photoelectric devices. Here, we propose a double-sided metamaterial structure to achieve double-zero refractive index in the terahertz region. We use the S parameter inversion algorithm to extract the equivalent electromagnetic parameters of the metamaterial. By optimizing the design of structural parameters, we show that the effective refractive index can be achieved to be near zero at 0.5 – 1.7 THz and at 2.7 – 3.4 THz. By monitoring the current density distribution and the near-field distribution on the surface of the structure, we prove that the metamaterial structure has obvious zero refractive index effect at 1.66 and 3.34 THz. In addition, the influence of geometric parameters of metamaterial structures on equivalent refractive index is revealed. [ABSTRACT FROM AUTHOR]

We propose a wideband linear polarization converter in transmission mode by bilayer metamaterial. The polarization converter operates from 0.55 to 1.37 THz with polarization conversion ratio maintaining nearly 100%. The distribution of surface current and electrical field was numerically simulated to clarify physical mechanism of polarization conversion. Importantly, we introduced the Stokes method to assess the polarization state of transmitted converter. The Fabry–Pérot-like cavity model was established to reveal the enhancement of polarization conversion ratio. The clear expressions including ideal and approximate model were deduced to provide an excellent explanation of Fabry–Pérot cavity in subwavelength bilayer metamaterials structure. [ABSTRACT FROM AUTHOR]

Computed Tomographic Imaging Spectrometer (CTIS) has the advantages of both computed tomography technology and snapshot spectroscopy and has potential applications in many fields. However, the development of CTIS has been limited by the volume issues of key components. In consideration of the compact structure of the metamaterial, an all-dielectric metamaterial array is studied as an alternative to optimize the structure of CTIS. The array can be used for snapshot-type optical imaging, with a wide working range of 550 nm ∼ 1000 nm. At the same time, the system design and simulation technology are studied by using the array, which provides a useful reference for the development of micro imaging spectrometer based on metamaterial. • Using metamaterials to realize the miniaturization of CTIS. • The metamaterial is first used to realize the CGH of CTIS. • The micro CTIS adapts to the lens size of the mobile phone. [ABSTRACT FROM AUTHOR]

One-dimensional metallic grating structure was proposed to realize high refractive index metamaterial in the terahertz region. By drastically increasing the effective permittivity by means of intense capacitive coupling and reducing the diamagnetic effect using a thin metallic thickness, a peak refractive index of 15.81 at the resonant frequency in embedded metallic grating can be obtained. Multiband high refractive index metamaterial can be realized by double symmetric metallic grating and asymmetric grating structure. For asymmetric grating metamaterial structure, two separate transmission peaks appear and result in two separate high refractive index. Interestingly, a near zero refractive index metamaterial can be obtained by the introduction of double asymmetric design. It was found that our designed ultrahigh refractive index metamaterials depend on the electric field coupling effect and the magnetic field diamagnetic response. [ABSTRACT FROM AUTHOR]

By drastically decreasing the diamagnetic effect with a thin window type structure in the unit cell and increasing the effective permittivity through strong capacitive coupling, we report a window-type broadband isotropic two-dimensional metamaterial with extremely high refractive index in the terahertz region. The designed peak index of refraction of near 18.22 at about 1.15 THz is predicted. In the experiment, we fabricated a “window” type structural metamaterial, and the measured transmission was compared with the results of the simulation. The effective refractive index for the prepared metamaterial was extracted by S-parameter extraction method. It is found that ultrahigh refractive index metamaterials depend on the electric field coupling effect, the magnetic field diamagnetic response, and the geometric parameters in the unit cell. Higher resonant frequency makes it possible to utilize broader high refractive index with low loss and large transmission. [ABSTRACT FROM AUTHOR]