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Microcavity lasers shaped as thin circular disks are famous for the ultra-low thresholds of their whispering-gallery (WG) modes. We considered a two-dimensional (2-D) model of such a laser in free space with a ring-like active region and compared the characteristics of its modes with the modes of an active microring, i.e. a similar disk with a concentric(More)
Our objective is the assessment of the accuracy of a conventional finite-difference time-domain (FDTD) code in the computation of the near- and far-field scattering characteristics of a circular dielectric cylinder. We excite the cylinder with an electric or magnetic line current and demonstrate the failure of the two-dimensional FDTD algorithm to(More)
The plane wave scattering and absorption by finite and infinite gratings of free-space standing graphene strips are studied in the THz range. Both finite and infinite gratings are studied. The formulation involves modified boundary conditions imposed on the strips. We build an accurate numerical solution to this problem based on the hyper-singular integral(More)
We investigate the lasing spectra, threshold gain values, and modal fields for a two-dimensional microcavity laser with a square contour defined by the super-circle equation. The cavity modes are considered accurately using the linear electromagnetic formalism of the Lasing Eigenvalue Problem (LEP) with exact boundary and radiation conditions. We reduce the(More)
The theory of electromagnetic eigenwaves propagating on open dielectric and metallic waveguides is reviewed. The main steps of the theoretical approach based on analytical regularization of the problem are outlined and discussed. Generalized eigenwave problems for lossless dielectric waveguides are considered more comprehensively as examples of such(More)
The problem of the H-polarized wave scattering by finite chains of circular nanowires is considered. A two-dimensional diffraction problem with rigorous boundary conditions is solved by partial separations of variables method using local polar coordinates of each scatterer. The obtained results demonstrate convergence of the algorithm and good agreement(More)
The plane wave scattering and absorption by an infinite flat graphene strip grating are studied in the THz range in the H and E-polarization regimes. Accurate numerical treatment is based on the dual series equations and the analytical regularization technique. In the H-polarization case, the dominant feature is the excitation of the surface plasmon(More)
The lasing modes in a thin kite-shaped active microcavity are considered as solutions to a specifically tailored two-dimensional (2-D) linear eigenvalue problem for the Maxwell equations with exact boundary and radiation conditions. This problem is reduced to the set of Muller's boundary integral equations discretized using the adequate quadrature formulas.(More)
We study the scattering of the H-polarized plane wave by a freestanding periodic grating that contains two circular cylinders on a single period, one made of silver and another dielectric. The reflection and transmission coefficients for such a grating demonstrate several types of resonances including plasmons and grating resonances. Besides, we analyze the(More)