Transmittance and resonance tunneling of the optical fields in the microspherical metal-dielectric structures

Abstract

We have numerically studied the transmittance of the metallo-dielectric spherical structure deposited on a microsphere in a frequency range where the dielectric permittivity of metal is negative. We have found an equidistant spectrum of the resonant peaks of almost completely transmittency. The position of the peaks is defined by the thickness of the dielectric layer, and the width of peaks sharply decreases with increases thickness of the metallic layer. We have explored the radial distribution of the electromagnetic field in such a stack and the spectrum of the eigenfrequencies. The amplitude of the field in the dielectric layers may exceed on 1 to 2 orders of magnitude the value of a field in the output of the structure. Such an effect opens the opportunity to use the microspheres coating by metallo-dielectric multilayers for an effective surface harmonic generation in the optical range and for a high-resolution frequency conversion in the bands of such resonances.