arXiv subjects

I. Velchev

Publications and source records attributed to I. Velchev.

4 recordsLinked to original sources

arXiv2009

Energy and information flow in superlensing

In the superlens problem, the presence of the reflected wave plays a critical role in the energy and information transfer from the object to recording device: both incident and reflected evanescent waves are required to insure nonzero energy/information flux from the object to the recorder. Therefore an optimization is required between the image quality (characterized by a transfer function) and information transfer rate (characterized by the energy/information flux). It is shown that the introduction of the recording device may lead to the deterioration in the image quality as compared to the ideal case when no recording device is present. The decline in the image quality is due to the generation of phase-shifted reflected evanescent wave between the lens and the recorder. It is also shown that the magnitude of the energy flux depends on the amount of dissipation in the lens and the recorder in a non-monotonous way.

physics.optics↗

arXiv2008

Laser-to-proton energy transfer efficiency in laser-plasma interactions

It is shown that the energy of protons accelerated in laser-matter interaction experiments may be significantly increased through the process of splitting the incoming laser pulse into multiple interaction stages of equal intensity. From a thermodynamic point of view, the splitting procedure can be viewed as an effective way of increasing the efficiency of energy transfer from the laser light to protons, which peaks for processes having the least amount of entropy gain. It is predicted that it should be possible to achieve $\apprge 100%$ increase in the energy efficiency in a six-stage laser proton accelerator compared to a single laser-target interaction scheme.

physics.plasm-ph↗

arXiv2006

Resonant transparency of materials with negative permittivity

It is shown that the transparency of opaque material with negative permittivity exhibits resonant behavior. The resonance occurs as a result of the excitation of the surface waves at slab boundaries. Dramatic field amplification of the incident evanescent fields at the resonance improves the resolution of the the sub-wavelength imaging system (superlens). A finite thickness slab can be totally transparent to a \textit{p}-polarized obliquely incident electromagnetic wave for certain values of the incidence angle and wave frequency corresponding to the excitation of the surface modes. At the resonance, two evanescent waves have a finite phase shift providing non-zero energy flux through the non-transparent region.

physics.optics↗

arXiv2006

Evanescent wave interference and the total transparency of a warm high-density plasma slab

It is shown that an overcritical density plasma slab can be totally transparent to a \textit{p}-polarized obliquely incident electromagnetic wave. High transparency is achieved due to the interference of the evanescent waves in the subcritical region. The transmission coefficient has the resonant character due to the excitation of a plasma surface mode (plasmon-polariton). It is crucial that two evanescent waves have certain phase shift to provide non-zero energy flux through non-transparent region. The required phase shift is obtained at the exact resonance and corresponds to the absolute transparency. In a warm plasma case, the excitation of the propagating longitudinal (electrostatic) modes becomes possible. We demonstrate that these longitudinal excitations facilitate the total transparency of an opaque plasma slab creating additional resonances in the transmission property of the system.

physics.plasm-ph↗