Leonid L. Doskolovich

Extraordinary magneto-optical effects and transmission through metal-dielectric plasmonic systems

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 Maxwells 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%.

Iteractive Methods For Diffractive Optical Elements Computation

1. Introduction 2. Generations of Wavefields Using Diffractive Optical Elements (DOEs) 3. Parametric Methods of Computing DOEs 4. Iterative Algorithms for Calculating DOEs Forming Radially Symmetrical Images 5. Iterative Algorithms for CalculatingWavefront Formers 6. Calculation of Phase Formers of Light Modes 7. Design of Multiorder Diffractive Gratings with a Pregiven Intensity of Diffractive Orders 8. Iterative Methods for Calculating Multifocus DOEs 9. Calculation of DOEs for Some SpecialApplications 10. Conclusion Appendices References Index.

Plasmon-mediated magneto-optical transparency

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.

Design of high-efficient freeform LED lens for illumination of elongated rectangular regions

We propose a method for the design of an optical element generating the required irradiance distribution in a rectangular area with a large aspect ratio. Application fields include streetlights, the illumination of halls or corridors, and so forth. The design assumes that the optical element has a complex form and contains two refractive surfaces. The first one converts a spherical beam from the light source to a cylindrical beam. The second one transforms an incident cylindrical beam and generates the required irradiance distribution in the target plane. Two optical elements producing a uniform irradiance distribution from a Cree® XLamp® source in rectangular regions of 17 m × 4 m and 17 m × 2 m are designed. The light efficiency of the designed optical element is larger than 83%, whereas the irradiance nonuniformity is less than 9%.

Design of DOEs for wavelength division and focusing

We propose a technique for calculating the color separation gratings aimed at separating plane light beams of different wavelengths into different diffraction orders. The technique is based on a special-type optimization criterion. With this criterion, the problem of calculating the piecewise-constant grating profile is reduced to sequentially solving independent problems of optimization of the step heights. We derived an analytical expression for the profile of a color separation grating that generalizes the familiar analytical solutions. The criterion introduced is used to design a diffractive optical element (DOE) that generates required light beams when it is illuminated by different wavelengths. Design of color separation gratings able to separate three and five different wavelengths and DOEs to demultiplex and focus the two- and three-wavelength beams is presented.

A method of designing diffractive optical elements focusing into plane areas

We propose a numerical method for designing phase function of diffractive optical elements (DOEs) aimed at focusing into a plane area of complex shape. The method is applied to factorable intensity distribution in the domain of focusing and factorable illuminating beam of arbitrary cross-section. The diffraction analysis of a direct problem of focusing into the plane region is carried out. Based on a specially developed software, the numerical experiment was carried out, which allowed us to find that the theoretical power efficiency of typical DOEs is no less than 85%.

Design of diffractive lenses for focusing surface plasmons

We present a method of designing diffractive optical elements for transforming and focusing surface plasmons. The method is based on a phase modulation of the surface plasmon provided by the dielectric block with varying geometric parameters located on the interface. The problem of SP diffraction by a dielectric block is solved using the rigorous coupled wave analysis. We demonstrate that the modulation can be implemented not only by changing the length of the dielectric block at fixed height, but also by changing the height at fixed length as well as by simultaneous changing of both parameters. The height modulation and combined height–length modulation are believed to be considered for the first time. As an example, the design of diffractive elements for focusing surface plasmons is considered. It is demonstrated that combining the height and length modulations allows us to increase the diffraction efficiency by more than 10%.

A DOE to form a line-shaped directivity diagram

Abstract Diffractive optical elements to form one-parameter directivity diagrams are designed using the geometric optics. The field ray structure corresponding to the line-shaped directivity diagram is analyzed and curvilinear coordinates for calculating the eikonal are proposed. A new simplified formula for the eikonal function in the curvilinear coordinates is derived. The calculation of the eikonal function is exemplified by the line-shaped and arc-shaped directivity diagram.

Computer Generated Diffractive Multi-focal Lens

The method has been proposed for computing Fresnel-type multi-focal lenses on the basis of special-type phase nonlinearity. A multi-focal lens is represented as a mathematical superposition of a thin lens and nonlinearity distorted Fresnel lens. Selection of the nonlinearity type is reduced to the problem of the groove form determination for the phase diffraction grating with pre-set energy distribution between orders. In particular, bi-focal lens and seven-focal lens have been investigated.

Scattering suppression in plasmonic optics using a simple two-layer dielectric structure

We demonstrate that a planar structure consisting of two isotropic dielectric layers can be used to minimize parasitic scattering in plasmonic elements. It is shown using rigorous electromagnetic simulations that the utilization of the proposed structure allows reducing the scattering losses by an order-of-magnitude (1%–2%). The proposed approach can be used for the design of various plasmonic elements such as lenses, reflectors, and plasmonic crystals.