ABSTRACT
A method for the design of reflecting surfaces generating prescribed continuous illuminance distributions in two-dimensional domains is proposed. The mirror surface is represented as an envelope of a two-parameter family of ellipsoids. The first focus of each ellipsoid coincides with the point light source, while the second one is located at the illuminated domain. This surface representation can be interpreted as a limiting case of a segmented surface used in the supporting quadric method for focusing onto a set of points. The envelope equation depends on the function defining the lengths of the major axes of the ellipsoids of the family. The calculation of this function is performed using a continuous approximation of a discrete function obtained from the solution of a discrete problem of focusing onto a set of points. High efficiency of the proposed method is illustrated by the designed examples of mirrors for generating uniform illuminance distributions in areas of different shapes.
ABSTRACT
Magnetic field control of light is among the most intriguing methods for modulation of light intensity and polarization on sub-nanosecond timescales. The implementation in nanostructured hybrid materials provides a remarkable increase of magneto-optical effects. However, so far only the enhancement of already known effects has been demonstrated in such materials. Here we postulate a novel magneto-optical phenomenon that originates solely from suitably designed nanostructured metal-dielectric material, the so-called magneto-plasmonic crystal. In this material, an incident light excites coupled plasmonic oscillations and a waveguide mode. An in-plane magnetic field allows excitation of an orthogonally polarized waveguide mode that modifies optical spectrum of the magneto-plasmonic crystal and increases its transparency. The experimentally achieved light intensity modulation reaches 24%. As the effect can potentially exceed 100%, it may have great importance for applied nanophotonics. Further, the effect allows manipulating and exciting waveguide modes by a magnetic field and light of proper polarization.
ABSTRACT
The WKB equations for the dynamics of the surface plasmon polariton (SPP) wavepacket are studied. The dispersion law for the SPP in a metal-dielectric heterostructure with varying thickness of a dielectric grating is rigorously calculated and investigated using the scattering matrix method. Two channels of the SPP wavepacket optical losses related to the absorption in a metal and to the SPP leakage are analyzed. It is shown that change of the dielectric layer thickness acts on the SPP as an external force leading to evolution of its quasimomentum and to the wavepacket reversal or even to optical Bloch oscillations (BO). Properties of these phenomena are investigated and discussed. Typical values of the BO amplitude are about tens of microns and the period is around tens or hundreds of femtoseconds.
ABSTRACT
Magneto-optical (MO) properties of perforated heterostructures consisting of a thin metallic film perforated with a periodic array of subwavelength slits and a smooth magnetic dielectric are investigated. Rigorous modeling revealed a magnetization-even MO effect determined by the relative change in the intensity of the transmitted or reflected light when the sample is magnetized in-plane perpendicularly to the slits. The effect takes its maximum value when the p-polarized incident light excites quasi-waveguided eigenmodes in the magnetic layer with the phase velocity close to the one of the TE mode in the nongyrotropic planar waveguide.
ABSTRACT
Color separation gratings (CSGs) are designed within the framework of the rigorous electromagnetic theory using a gradient method. The optimality of the scalar-theory-based solutions is estimated. The results of the experimental study of a CSG to separate three wavelengths are presented.
ABSTRACT
We predict theoretically a significant enhancement of the magneto-optical Faraday and Kerr effects in the bilayer systems of a metallic film perforated with subwavelength hole arrays and a uniform dielectric film magnetized perpendicular to its plane. Calculations, based on a rigorous coupled-wave analysis of Maxwell's equations, demonstrate that in such structures the Faraday effect spectrum has several resonance peaks in the near-infrared range, some of them coinciding with transmittance peaks, providing simultaneous large Faraday rotation enhanced by an order of magnitude and high transmittance of about 35%.
