Asaf Farhi

Exact analysis of a Veselago lens in the quasi-static regime

The resolution of conventional optical lenses is limited by the wavelength. Materials with negative refractive index have been shown to enable the generation of an enhanced resolution image where both propagating and non-propagating waves are employed. We analyze such a Veselago lens by exploiting some exact one dimensional integral expressions for the quasi-static electric potential of a point charge in that system. Those were recently obtained by expanding that potential in the quasi-static eigenfunctions of a three-?at-slabs composite structure. Numerical evaluations of those integrals, using realistic values for physical parameters like the electric permittivities of the constituent slabs and their thickness, reveal some surprising e?ects: E.g., the maximum concentration of the electric ?eld occurs not at the geometric optics foci but at the interfaces between the negative permittivity slab and the positive permittivity slabs. The analysis provides simple computational guides for designing such structures in order to achieve enhanced resolution of an optical image.

Generating an electromagnetic multipole by oscillating currents

Based on the relation between a plane phased array and plane waves we show that a spherical current layer or a current sphere proportional to a multipole electric field and situated in a uniform medium generates the same multipole field in all space. We calculate TE and TM multipoles inside and outside the spherical layer. The

Calculation of molecular free energies in classical potentials

l=1

Eigenstate expansion of the quasistatic electric field of a point charge in a spherical inclusion structure

TM multipoles are localized at the origin with a focal spot with full width at half maximum of

A novel method for calculating relative free energy of similar molecules in two environments

0.4\lambda

General eigenstates of Maxwell's equations in a two-constituent composite medium

in the lateral axes and

General eigenstates of Maxwell's equations in a two-constituent composite medium and their application to a calculation of the local electric field in a flat-slab microstructure

0.58\lambda

Non-quasi-static eigenstates of Maxwell's equations in a two-constituent composite medium and their application to a calculation of the local electric field of an oscillating dipole

in the vertical axis. The multipole fields near the origin are prescriptions for the current distributions required to generate those multipole fields. A spherical layer can couple to a multipole source since the oscillation of the electrons in the layer due to the multipole field generates the multipole field in all space, which in turn can drive the multipole currents. Exciting a multipole in a polarizable sphere or spherical layer can couple it to another polarizable sphere or spherical layer.

Perfect optical imaging of a Veselago Lens: Eigenstate-based analysis

Free energies of molecules can be calculated by quantum computations or by normal mode classical calculations. However, the first can be computationally impractical for large molecules and the second is based on the assumption of harmonic dynamics. We present a novel, accurate and complete calculation of molecular free energies in standard classical potentials. In this method we transform the molecule by relaxing potential terms which depend on the coordinates of a group of atoms in that molecule and calculate the free energy difference associated with the transformation. Then, since the transformed molecule can be treated as non interacting systems, the free energy associated with these atoms is analytically or numerically calculated. This two-step calculation can be applied to calculate free energies of molecules or free energy difference between (possibly large) molecules in a general environment. We suggest the potential application of free energy calculation of chemical reactions in classical molecular simulations.

Electromagnetic eigenstates and the field of an oscillating point electric dipole in a flat-slab composite structure

A point charge in the presence of a metallic nanoshpere is a fundamental setup, which has implications for Raman scattering, enhancement of spontaneous emission of a molecule by an antenna, sensing, and modeling a metallic tip in proximity to a nanoparticle. Here, we analytically expand the electric field of a point charge in an