23 research outputs found
\u3cem\u3ePTM\u3c/em\u3e Metamaterials via Complex-Coordinate Transformation Optics
We extend the transformation-optics paradigm to a complex spatial coordinate domain, in order to deal with electromagnetic metamaterials characterized by balanced loss and gain, giving special emphasis to parity-time (PT) symmetric metamaterials. We apply this general theory to complex-source-point radiation and anisotropic transmission resonances, illustrating the capability and potentials of our approach in terms of systematic design, analytical modeling, and physical insights into complex-coordinate wave objects and resonant states
Magnified imaging based on non-Hermitian nonlocal cylindrical metasurfaces
We show that a cylindrical lensing system composed of two metasurfaces with suitably tailored non-Hermitian
(i.e., with distributed gain and loss) and nonlocal (i.e., spatially dispersive) properties can perform magnified
imaging with reduced aberrations. More specifically, we analytically derive the idealized surface-impedance
values that are required for “perfect” magnification and imaging and elucidate the role and implications of non-
Hermiticity and nonlocality in terms of spatial resolution and practical implementation. For a basic demonstration,
we explore some proof-of-principle quasilocal and multilayered implementations and independently validate the
outcomes via full-wave numerical simulations. We also show that the metasurface frequency-dispersion laws
can be chosen so as to ensure unconditional stability with respect to arbitrary temporal excitations. These
results, which extend previous studies on planar configurations, may open intriguing venues in the design of
metastructures for field imaging and processing
Magnified imaging based on non-Hermitian nonlocal cylindrical metasurfaces
We show that a cylindrical lensing system composed of two metasurfaces with suitably tailored non-Hermitian
(i.e., with distributed gain and loss) and nonlocal (i.e., spatially dispersive) properties can perform magnified
imaging with reduced aberrations. More specifically, we analytically derive the idealized surface-impedance
values that are required for “perfect” magnification and imaging and elucidate the role and implications of non-
Hermiticity and nonlocality in terms of spatial resolution and practical implementation. For a basic demonstration,
we explore some proof-of-principle quasilocal and multilayered implementations and independently validate the
outcomes via full-wave numerical simulations. We also show that the metasurface frequency-dispersion laws
can be chosen so as to ensure unconditional stability with respect to arbitrary temporal excitations. These
results, which extend previous studies on planar configurations, may open intriguing venues in the design of
metastructures for field imaging and processing
Analytical Study of Sub-Wavelength Imaging by Uniaxial Epsilon-Near-Zero Metamaterial Slabs
We discuss the imaging properties of uniaxial epsilon-near-zero metamaterial
slabs with possibly tilted optical axis, analyzing their sub-wavelength
focusing properties as a function of the design parameters. We derive in closed
analytical form the associated two-dimensional Green's function in terms of
special cylindrical functions. For the near-field parameter ranges of interest,
we are also able to derive a small-argument approximation in terms of simpler
analytical functions. Our results, validated and calibrated against a full-wave
reference solution, expand the analytical tools available for
computationally-efficient and physically-incisive modeling and design of
metamaterial-based sub-wavelength imaging systems.Comment: 25 pages, 9 figures (modifications in the text; two figures and
several references added