MiraTechnologies Ltd.

Bucharest, Romania

MiraTechnologies Ltd.

Bucharest, Romania

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Apostol M.,Institute of Atomic Physics of romenia | Apostol M.,MiraTechnologies Ltd. | Ilie S.,MiraTechnologies Ltd. | Petrut A.,MiraTelecom | And 2 more authors.
Journal of Applied Physics | Year: 2012

The static dipolar force is generalized to time-dependent classical distributions of dipoles and electromagnetic fields. This force may exhibit a remarkable resonance character for induced dipoles, related to the pole structure of the polarizabilities. The resonance phenomenon is illustrated for two macroscopic polarizable bodies, with mutually induced polarizations, using the well-known Lorentz-Drude model for the dielectric response with optical dispersion and a characteristic (resonance) frequency. Specifically, the calculations are performed for distances much longer than the dimension of the bodies (point-like bodies), but shorter than the characteristic wavelength (sub-wavelength, stationary, near-field regime). The polarizations are induced via a localized external field acting upon only one body. The force is practically vanishing for distinct substances and acquires a non-vanishing value for identical substances. It falls off as the 7-th power of the distance, being reminiscent of the van der Waals-London force. The conditions of validity of this resonance phenomenon are emphasized. Particular cases corresponding to independent external fields or two isolated, interacting bodies (closed system) are also analyzed, with similar conclusions regarding the resonance character of the force. © 2012 American Institute of Physics.


Apostol M.,Institute of Atomic Physics of romenia | Apostol M.,MiraTechnologies Ltd | Ilie S.,MiraTechnologies Ltd | Petrut A.,MiraTelecom | And 2 more authors.
Advanced Electromagnetics | Year: 2013

The polarization and magnetization degrees of freedom are included in the general treatment of the electromagnetic field in matter, and their governing equations are given. Particular cases of solutions are discussed for polarizable, non-magnetic matter, including quasi-static fields, surface plasmons, propagation, zero-point fluctuations of the eigenmodes, especially for a semi-infinite homogeneous body (half-space). The van derWaals-London-Casimir force acting between a neutral nano-particle and a half-space is computed and the response of this electromagnetically coupled system to an external field is given, with relevance for the surface enhanced Raman scattering. © 2013, Tarbiat Modares University. All rights reserved.


Apostol M.,Institute of Atomic Physics of romenia | Apostol M.,MiraTechnologies Ltd | Ilie S.,MiraTechnologies Ltd | Petrut A.,MiraTelecom | And 2 more authors.
Applied Physics A: Materials Science and Processing | Year: 2014

A simple model of coupled plasmons arising in two neighbouring nano-particles is presented. The coupled oscillations and the corresponding eigenfrequencies are computed. It is shown that the plasmons may be periodically transferred between the two particles. For larger separation distances between the two particles the retardation is included. The oscillation eigenmodes are the polaritons in this case. There are distances for which the particles do not couple to each other, i.e. the polaritonic coupling gets damped. The van der Waals-London-Casimir force is estimated for the two particles; it is shown that for large distances the force is repulsive. We compute also the polarizabilities of the two coupled nano-particles and their cross-section under the action of an external monochromatic plane wave, which exhibit resonances indicative of light trapping and field enhancement. A resonant force is also identified, acting upon the particles both on behalf of the external field and of each other. © 2013 Springer-Verlag Berlin Heidelberg.


Apostol M.,Institute of Atomic Physics of romenia | Apostol M.,MIRA Technologies Ltd. | Ilie S.,MIRA Technologies Ltd. | Petrut A.,MIRA Telecom | And 2 more authors.
EPJ Applied Physics | Year: 2012

A model of heterogeneous, composite material is introduced, consisting of randomly distributed identical structural micro-domains endowed with electric charges or dipoles. Two cases are presented, one corresponding to a tightly packed (dense) material, another corresponding to highly-dispersed, small domains. The polarizability is computed in both cases, under the action of an external uniform electric field oscillating in time (a quasi-stationary field), and it is related to the displacement of the micro-domains from their positions of local equilibrium (translations or rotations). It is shown that the polarizability (or electric susceptibility) can exhibit characteristic (resonance) frequencies in the radio-frequency range and, even for moderate external fields, the material can undergo a displacive transition (similar to a ferroelectric transition), governed by non-linearities in the interaction energy of the micro-domains. The shift in the characteristic frequencies of the polarizability is estimated, as caused by the displacive modification. © EDP Sciences, 2012.

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