Transition to lasing induced by resonant absorption

We theoretically demonstrate that increase of absorption with constant gain in laser systems can lead to onset of laser generation. This counter-intuitive absorption induced lasing (AIL) is explained by emergence of additional lasing modes created by an introduction of an absorbing medium with narrow linewidth. We show that this effect is universal and can be encountered in simple Fabry-Perot-like systems and doped spherical dielectric nanoresonators. The predicted behavior is robust against frequency detuning between the gain and absorbing medium

Sub-wavelength imaging: Resolution enhancement using metal wire gratings

An experimental evidence of subwavelength imaging with a "lens", which is a uniaxial negative permittivity wire medium slab, is reported. The slab is formed by gratings of long thin parallel conducting cylinders. Taking into account the anisotropy and spatial dispersion in the wire medium we theoretically show that there are no usual plasmons that could be exited on surfaces of such a slab, and there is no resonant enhancement of evanescent fields in the slab. The experimentally observed clear improvement of the resolution in the presence of the slab is explained as filtering out the harmonics with small wavenumbers. In other words, the wire gratings (the wire medium) suppress strong traveling-mode components increasing the role of evanescent waves in the image formation. This effect can be used in near-field imaging and detection applications.Comment: 12 pages, 6 figure

Inverse Borrmann effect in photonic crystals

The Borrmann effect, which is related to the microscopic distribution of the electromagnetic field inside the primitive cell, is studied in photonic and magnetophotonic crystals. This effect, well-known in x-ray spectroscopy, is responsible for the enhancement or suppression of various linear and nonlinear optical effects when the incidence angle and/or the frequency change. It is shown that by design of the primitive cell this effect can be suppressed and even inverted

Электронные состояния в металло-полимерном композите полипараксилилен - серебро

Cathodoluminescence spectra of polyparaxylylene - silver metallopolymeric composite were measured and analyzed. The band structure of the composite was investigated. The density of states and band gap were calculated. A model of energy transfer in the polymer matrix was suggested.Измерены и проанализированы спектры катодолюминесценции металлополимерного композита полипараксилилен-серебро, исследована зонная структура композита, рассчитана плотность состояний и ширина запрещенной зоны, предложена модель переноса энергии в полимерной матрице