Em. E. Kriezis

High numerical aperture vectorial imaging in coherent optical microscopes

Imaging systems are typically partitioned into three components: focusing of incident light, scattering of incident light by an object and imaging of scattered light. We present a model of high Numerical Aperture (NA) imaging systems which differs from prior models as it treats each of the three components of the imaging system rigorously. It is well known that when high NA lenses are used the imaging system must be treated with vectorial analysis. This in turn requires that the scattering of light by the object be calculated rigorously according to Maxwells equations. Maxwells equations are solvable analytically for only a small class of scattering objects necessitating the use of rigorous numerical methods for the general case. Finally, rigorous vectorial diffraction theory and focusing theory are combined to calculate the image of the scattered light. We demonstrate the usefulness of the model through examples.

A 320 Gb/s-Throughput Capable 2

We demonstrate a 2 × 2 silicon-plasmonic router architecture with 320 Gb/s throughput capabilities for optical interconnect applications. The proposed router platform relies on a novel dual-ring Dielectric-Loaded Surface Plasmon Polariton (DLSPP) 2 × 2 switch heterointegrated on a Silicon-on-Insulator (SOI) photonic motherboard that is responsible for traffic multiplexing and header processing functionalities. We present experimental results of a Poly-methyl-methacrylate (PMMA)-loaded dual-resonator DLSPP waveguide structure that uses two racetrack resonators of 5.5 μm radius and 4 μ m-long straight sections and operates as a passive add/drop filtering element. We derive its frequency-domain transfer function, confirm its add/drop experimental spectral response, and proceed to a circuit-level model for dual-ring DLSPP designs supporting 2 × 2 thermo-optic switch operation. The validity of our circuit-level modeled 2 × 2 thermo-optic switch is verified by means of respective full vectorial three-dimensional Finite Element Method (3D-FEM) simulations. The router setup is completed by means of two 4 × 1 SOI multiplexing circuits, each one employing four cascaded second order micro-ring configurations with 100 GHz spaced resonances. Successful interconnection between the DLSPP switching matrix and the SOI circuitry is performed through a butt-coupling design that, as shown via 3D-FEM analysis, allows for small coupling losses of as low as 2.6 dB. The final router architecture is evaluated through a co-operative simulation environment, demonstrating successful 2 × 2 routing for two incoming 4-wavelength Non-Return-to-Zero (NRZ) optical packet streams with 40 Gb/s line-rates.

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The diffraction of electromagnetic radiation from one-dimensional planar transmittive screens illuminated by Gaussian-profile beams is examined. The incident Gaussian beam is expressed as a superposition of elementary plane waves that propagate along different directions, with the aid of the plane-wave spectrum technique based on Fourier optics. For each elementary plane wave, the diffracted field is obtained by applying the spectral domain method combined with the method of moments. Results for the cases of normal and oblique incidence are in agreement with theoretically expected properties of such planar screens and are found to be very sensitive to the aspect ratio γ (strip width to period). The diffracted beam is composed of distinct subbeams that propagate along specific directions. These directions coincide with the Floquet harmonics generated by an incident plane wave propagating along the same direction as the initial beam.

2 Silicon-Plasmonic Router Architecture for Optical Interconnects

A full vector beam propagation method based on the split-operator approach is developed for 3-D z-dependent structures. The inherent coupling of the three electric field components found in the vector wave equation, which stems from the variation of the refractive index along the axial z/spl circ/ direction, is fully taken into consideration. Three distinct procedures are proposed for the numerical implementation based on the FFT, Pade approximation, and alternating direction implicit (ADI), respectively. Typical integrated optics applications are considered in order to verify and assess the applicability of the method.

DIFFRACTION OF A GAUSSIAN BEAM FROM A PERIODIC PLANAR SCREEN

A full vectorial beam propagation scheme is developed and it is applied on 3-dimensional waveguide structures. The formulation is based on the coupled wave equations for the transverse electric field. Each propagation step is performed by utilizing both the FFT and a finite-difference implementation. Under this perspective the offered advantages of FFT and finite-differences are exploited within a single propagation step resulting in a joint propagation scheme. The scheme is applied on a step-index circular fiber where analytical solutions are readily available for cross-checking. Moreover, the dependence of the phase constant on the reference refractive index is discussed. The polarized modes and the effective mode indices are derived in the case of rib waveguides by performing propagation along imaginary distance. Further, the rib waveguide coupler is examined and the energy transfer is simulated. >

A three-dimensional full vectorial beam propagation method for z-dependent structures

Review of the equations of electromagnetic field geometrical optics ray theory planar dielectric waveguides fibres resonators Gaussian beam laser Fourier optics scalar theory of diffraction optical holography optical radiation optical techniques in remote sensing nonlinear optics.

A joint finite-difference and FFT full vectorial beam propagation scheme

ContentsIt is well known that inside a conducting medium eddy currents are induced when an excitation of a time varying current source is placed in the vicinity of this medium. It is also of a great interest the examination of the problem related to the motion of an exciting source and the induced eddy currents within a conducting material placed close to the moving source. The determination of the eddy current density and the field outside the conducting material due to the eddy currents gives the possibility of calculating the lift and drag force acting on the moving system.ÜbersichtEs ist wohl bekannt, daß innerhalb von einem leitenden Medium Wirbelströme induziert werden, wenn in der Nähe dieses Mediums eine zeitlich veränderliche Stromerregung vorhanden ist. Die Probleme also, die die Bewegung einer Erregungsquelle und die dadurch induzierten Wirbelströme innerhalb eines leitenden Mediums in der Nähe der Erregung betreffen, sind von großem Interesse. Die Bestimmung der Wirbelstromdichte und des Feldes außerhalb des leitenden Materials infolge der Wirbelströme ermöglicht die Bestimmung der Trag- und Bremskräfte, die auf das sich bewegende Teil wirken.

Electromagnetics and optics

A full vector beam propagation method, which is based on the split-operator approach, is developed and it is applied on 3-D z-dependent structures. The coupling between the transverse and axial components of the electric field, which stems from the variation of the refractive index along the direction of propagation, is fully retained. Various numerical implementations are proposed and assessed. Numerical applications are from the field of integrated optics.

Determination of the field and the forces on a current filament moving above a conducting plate

Exact knowledge of the refractive-index profile of optical fibers and ion-exchange glass waveguides is needed for accurate calculation of their electromagnetic properties. Since there are always uncertainties in the manufacturing process, various methods have been proposed for the calculation of the refractive-index profile. All of these methods however, give only approximate results, and the electromagnetic properties of these devices are not always calculated with the required accuracy. A method to compensate for this inaccuracy is presented, with the addition of a small random term to the approximate estimation of the refractive-index profile. The contribution of this random term to the electromagnetic properties of the device under study is calculated with the aid of an expansion to the well-known fast Fourier transform beam propagation method.

Full vector beam propagation method for axially dependent 3-D structures

A hybrid iterative technique for the analysis of plane-wave diffraction from metallic gratings of arbitrary profile is presented. The finite-element method is used to model the field in the interior (groove) region, and the Floquet space harmonics expansion is used in the exterior region. Coupling of the two solutions is performed by the subregion iterative technique. In this way the symmetry and sparsity of the finite-element equations are fully exploited, and the number of Floquet harmonics can be set independent of the finite-element grid. Application to a rectangular and a sawtooth grating verifies the effectiveness of the proposed method.