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Transformation optics

About: Transformation optics is a research topic. Over the lifetime, 2687 publications have been published within this topic receiving 102378 citations.


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TL;DR: It is demonstrated theoretically that electromagnetic fields of certain frequencies can be parametrically shielded by a nonlinear left-handed material slab, where the permittivity and permeability are both negative.
Abstract: An analytical theory is developed for parametric interactions in metamaterial multilayer structures with simultaneous nonlinear electronic and magnetic responses and with a near-zero refractive index. We demonstrate theoretically that electromagnetic fields of certain frequencies can be parametrically shielded by a nonlinear left-handed material slab, where the permittivity and permeability are both negative. The skin depth is tunable, and even in the absence of material absorption, can be much less than the wavelength of the electromagnetic field being shielded. This exotic behavior is a consequence of the intricate nonlinear response in the left-handed materials and vanishing optical refractive index at the pump frequency.

34 citations

Journal ArticleDOI
TL;DR: In this article, an anisotropic terahertz active metamaterial device with an ultrasensitive modulation feature is proposed and experimentally studied, with a frequency shift of 0.26 ǫ in its sharp transparent windows by polarization rotation.
Abstract: Active control of metamaterial properties with high tunability of both resonant intensity and frequency is essential for advanced terahertz (THz) applications, ranging from spectroscopy and sensing to communications. Among varied metamaterials, plasmon-induced transparency (PIT) has enabled active control with giant sensitivity by embedding semiconducting materials. However, there is still a stringent challenge to achieve dynamic responses in both intensity and frequency modulation. Here, an anisotropic THz active metamaterial device with an ultrasensitive modulation feature is proposed and experimentally studied. A radiative-radiative-coupled PIT system is established, with a frequency shift of 0.26 THz in its sharp transparent windows by polarization rotation. Enabled by high charge-carrier mobility and longer diffusion lengths, we utilize a straightforwardly spin-coated MAPbI3 film acting as a photoactive medium to endow the device with high sensitivity and ultrafast speed. When the device is pumped by an ultralow laser fluence, the PIT transmission windows at 0.86 and 1.12 THz demonstrate a significant reduction for two polarizations, respectively, with a full recovery time of 561 ps. In addition, we numerically prove the validity that the investigated resonator structure is sensitive to the optically induced conductivity. The hybrid system not only achieves resonant intensity and frequency modulations simultaneously, but also preserves the all-optical-induced switching merits with high sensitivity and speed, which enriches multifunctional subwavelength metamaterial devices at THz frequencies.

34 citations

Journal ArticleDOI
TL;DR: It is demonstrated theoretically how perfect redshifting or blueshifting of an electromagnetic wave can be achieved without the creation of sidebands with a device of finite length.
Abstract: According to general relativity, the frequency of electromagnetic radiation is altered by the expansion of the universe. This effect-commonly referred to as the cosmological redshift-is of utmost importance for observations in cosmology. Here we show that this redshift can be reproduced on a much smaller scale using an optical analogue inside a dielectric metamaterial with time-dependent material parameters. To this aim, we apply the framework of transformation optics to the Robertson-Walker metric. We demonstrate theoretically how perfect redshifting or blueshifting of an electromagnetic wave can be achieved without the creation of sidebands with a device of finite length.

34 citations

Journal ArticleDOI
TL;DR: In this paper, a simplified quadratic cloak has been proposed which provides finite material properties at the inner radius of the cloak and impedance match with the free space at the outer radius of a cloak simultaneously.
Abstract: The presence of extreme material properties and undesired scattering make practical implementation of transformation optics based cloaks an extremely challenging issue. To overcome these problems, a simplified quadratic cloak has been proposed which provides finite material properties at the inner radius of the cloak and impedance match with the free space at the outer radius of the cloak simultaneously. The simultaneous occurrence of finite material properties and impedance match with the free space at the respective boundaries reduces the scattering cross section significantly. The material properties of the proposed simplified quadratic cloak can be realized with two dimensional (2D) metamaterials. The performance of the proposed cloak is examined by plotting the normalized total scattering cross section (SCSt,norm), and the scattering patterns in azimuthal plane. The proposed simplified quadratic cloak shows 10 dB reduction of the scattered field in both the forward and backward directions with respec...

34 citations

Journal ArticleDOI
TL;DR: It is demonstrated that for wavelengths leading to ℜ(εz) ≈ 0, near-perfect absorption arises and persists over a range of frequencies and subwavelength structure thicknesses.
Abstract: We investigate the interaction of polarized electromagnetic waves with hyperbolic metamaterial structures, whereby the in-plane permittivity component $\epsilon_x$ is opposite in sign to the normal component $\epsilon_z$. We find that when the thickness of the metamaterial is smaller than the wavelength of the incident wave, hyperbolic metamaterials can absorb significantly higher amounts of electromagnetic energy compared to their conventional counterparts. We also demonstrate that for wavelengths leading to $\Re(\epsilon_z) \approx 0$, near-perfect absorption arises and persists over a range of frequencies and subwavelength structure thicknesses.

34 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202324
202269
202147
202070
2019100
201890