D Kh Nurligareev

Bragg diffraction of light in a restricted homogeneous system of tunnel-coupled waveguides

A system of tunnel-coupled rectilinear waveguides is studied. The dependence of the number of modes in this system on the number of waveguides N, the distance between the waveguides, and the number of modes in a separate waveguide is considered. It is shown that the modes of the m = N and N + 1 orders in such a system are Bragg modes; i.e., the angle between the direction of their propagation and the system axis is close to the Bragg angle. The effective refractive indices n* of these modes change stepwise. The step size Δn* is found to be dependent on the distance s between the waveguides and on the number of modes in a separate waveguide. A system of single-mode waveguides with the number of guided modes M = 34 < N = 50 is studied experimentally. It is shown that the Bragg modes of the system lie among the leakage modes of the system and have rather low losses. It is demonstrated that the localization of the Bragg modes among the leakage modes may be favorable for their selection upon light generation.

Quasi-Resonant Enhancement of the Extinction Ratio in the Amorphous Silicon Nanowire Grid Polarizer

Spectral characteristics of thin-film nanowire grid polarizers based on amorphous silicon are numerically investigated. The extinction ratio, transmission coefficients, and reflection coefficients are calculated using the MC Grating code based on the rigorous coupled-wave analysis. It is found out that at particular structure parameters of the nanowire grid polarizer the extinction ratio increases to 106 at the optical radiation wavelength of about 380 nm, which is characterized as a quasi-resonance effect. A dissipative-interference qualitative interpretation of this effect within the waveguide model is proposed. This interpretation is confirmed by the calculated field distribution patterns in the vicinity of the quasiresonance.

Technique for determining the cell parameters of the confined one-dimensional photonic crystal, based on the Floquet-Bloch formalism

The technique for determining the cell structural parameters of the confined one-dimensional photonic crystal, based on the strict analytical representation of Floquet-Bloch waves in the form of inhomogeneous waves is proposed.

Leaky modes and directed modes in confined one-dimensional photonic crystal

Directed modes and leaky modes in a confined one-dimensional photonic crystal are analytically described. The dispersion relation of these modes is written as the transverse resonance condition of Floquet-Bloch waves, taking into account phase shifts at interfaces with adjacent media.