Sub-wavelength imaging with a left-handed material flat lens

We study numerically, by means of the pseudospectral time-domain method, the unique features of imaging by a flat lens made of a left-handed metamaterial that possesses the property of negative refraction. We confirm the earlier finding that a left-handed flat lens can provide near-perfect imaging of a point source and a pair of point sources with clear evidence of the sub-wavelength resolution. We illustrate the limitation of the resolution in the time-integrated image due to the presence of surface waves.Comment: 4 pages, RevTeX, 6 figures; added references and some discussio

Finite-Difference and Pseudospectral Time-Domain Methods Applied to Backwards-Wave Metamaterials

Backwards-wave (BW) materials that have simultaneously negative real parts of their electric permittivity and magnetic permeability can support waves where phase and power propagation occur in opposite directions. These materials were predicted to have many unusual electromagnetic properties, among them amplification of the near-field of a point source, which could lead to the perfect reconstruction of the source field in an image [J. Pendry, Phys. Rev. Lett. \textbf{85}, 3966 (2000)]. Often systems containing BW materials are simulated using the finite-difference time-domain technique. We show that this technique suffers from a numerical artifact due to its staggered grid that makes its use in simulations involving BW materials problematic. The pseudospectral time-domain technique, on the other hand, uses a collocated grid and is free of this artifact. It is also shown that when modeling the dispersive BW material, the linear frequency approximation method introduces error that affects the frequency of vanishing reflection, while the auxiliary differential equation, the Z transform, and the bilinear frequency approximation method produce vanishing reflection at the correct frequency. The case of vanishing reflection is of particular interest for field reconstruction in imaging applications.Comment: 9 pages, 8 figures, accepted by IEEE Transactions on Antennas and Propagatio

Bistable diode action in left-handed periodic structures

We study nonlinear transmission of an asymmetric multilayer structure created by alternating slabs of two materials with positive and negative refractive index. We demonstrate that such a structure exhibits passive spatially nonreciprocal transmission of electromagnetic waves, the analogue of the electronic diode. We study the properties of this left-handed diode and confirm its highly nonreciprocal and bistable transmittance by employing direct simulations.Comment: 4 pages, 5 figure

Muslim Women in Interfaith Partnerships in Germany

The number of Muslim-interfaith couples in European countries has become significant due to transnational migration and a growing number of Muslims living in Muslim Minority countries. While the challenges for partners in such unions are complex, this article focuses on the lived experiences of Muslim women in interfaith intimate relationships in Germa ny. Drawing on field interviews with women in mixed-faith relationships, the following questions are central: How do Muslim women conceptualize religious identity and practices? Do they face challenges from different groups (Muslim communities, their families, friends, etc.) and if so, how do these challenges manifest? If respondents create concepts of being Muslim for themselves, how do these evolve in their narratives? How do they question, adapt or discard theological and social demands? Preliminary results illustrate that some respondents would appreciate a Muslim community that accepts their positionality as intermarried Muslim women. Looking at the narration of religious practices and concepts of Muslimness in the interviews, it becomes clear that a classification as haram, or legally forbidden, puts a simple categorical bar in front of a socially and theologically complex context. The inquiry combines interview analysis with situational mapping and is informed by Grounded Theory methodology.Peer Reviewe

Tunable transmission and bistability in left-handed bandgap structures

We study the defect-induced nonlinear transmission of a periodic structure created by alternating slabs of two materials with positive and negative refractive index. We demonstrate bistable switching and tunable nonlinear transmission in a novel type of bandgap that corresponds to the vanishing average refractive index, and compare the observed effects for two types of the bandgaps.Comment: 3 pages, 5 figures; significant change

The Zero-n Gap Soliton

Periodic structures consisting of alternating layers of positive index and negative index materials possess a novel band gap at the frequency at which the average refractive index is zero. We show that in the presence of a Kerr nonlinearity, this zero-n gap can switch from low transmission to a perfectly transmitting state, forming a nonlinear resonance or gap soliton in the process. This zero-n gap soliton is omnidirectional in contrast to the usual Bragg gap soliton of positive index periodic structure

Wave scattering by metamaterial wedges and interfaces

We outline specific features of numerical simulations of metamaterial wedges and interfaces. We study the effect of different positioning of a grid in the Yee method, which is necessary to obtain consistent convergence in modeling of interfaces with metamaterials characterized by negative dielectric permittivity and negative magnetic permeability. We demonstrate however that, in the framework of the continuous-medium approximation, wave scattering on the wedge may result in a resonant excitation of surface waves with infinitely large spatial frequencies, leading to non-convergence of the simulation results that depend on the discretization step.Comment: 12 pages, 9 figure