14 research outputs found
|\epsilon|-Near-Zero materials in the near-infrared
We consider a mixture of metal coated quantum dots dispersed in a polymer
matrix and, using a modified version of the standard Maxwell-Garnett mixing
rule, we prove that the mixture parameters (particles radius, quantum dots
gain, etc.) can be chosen so that the effective medium permittivity has an
absolute value very close to zero in the near-infrared, i.e. |Re(epsilon)|<<1
and |Im (epsilon)|<<1 at the same near-infrared wavelength. Resorting to
full-wave simulations, we investigate the accuracy of the effective medium
predictions and we relate their discrepancy with rigorous numerical results to
the fact that |epsilon|<<1 is a critical requirement. We show that a simple
method for reducing this discrepancy, and hence for achieving a prescribed
value of |\epsilon|, consists in a subsequent fine-tuning of the nanoparticles
volume filling fraction.Comment: 3 pages, 3 figure
Mathematical analysis of the two dimensional active exterior cloaking in the quasistatic regime
We design a device that generates fields canceling out a known probing field
inside a region to be cloaked while generating very small fields far away from
the device. The fields we consider satisfy the Laplace equation, but the
approach remains valid in the quasistatic regime in a homogeneous medium. We
start by relating the problem of designing an exterior cloak in the quasistatic
regime to the classic problem of approximating a harmonic function with
harmonic polynomials. An explicit polynomial solution to the problem was given
earlier in [Phys. Rev. Lett. 103 (2009), 073901]. Here we show convergence of
the device field to the field needed to perfectly cloak an object. The
convergence region limits the size of the cloaked region, and the size and
position of the device.Comment: submitted to Analysis and Mathematical Physic
Electronic beam shifts in monolayer graphene superlattice
Electronic analogue of generalized Goos-H\"{a}nchen shifts is investigated in
the monolayer graphene superlattice with one-dimensional periodic potentials of
square barriers. It is found that the lateral shifts for the electron beam
transmitted through the monolayer graphene superlattice can be negative as well
as positive near the band edges of zero- gap, which are different from
those near the band edges of Bragg gap. These negative and positive beam shifts
have close relation to the Dirac point. When the condition () is satisfied, the beam shifts can be controlled from
negative to positive when the incident energy is above the Dirac point, and
vice versa. In addition, the beam shifts can be greatly enhanced by the defect
mode inside the zero- gap. These intriguing phenomena can be verified
in a relatively simple optical setup, and have potential applications in the
graphene-based electron wave devices.Comment: 5 pages, 4 figures, submitted on Oct. 15, 201
Electromagnetic metamaterial-inspired band gap and perfect transmission in semiconductor and graphene-based electronic and photonic structures
Invisibility of a metamaterial cloak illuminated by spherical electromagnetic wave
10.1007/s00339-009-5092-7Applied Physics A: Materials Science and Processing953881-888APAM