Ternary comb-like silicon photonic crystal: Oxidation, intrinsic modes, reflection windows and contrastivity
A ternary photonic crystal - A/B/A/C periodic structure is investigated analytically and numerically in the framework of transfer matrix formalism. The influence of oxidation to photonic gaps and positions of reflection windows for (SiO2/Si/SiO2/Air)N structure is calculated. It was shown that intrinsic optical contrastivity has a non-monotone behavior during the process of oxidation of silicon. The found results will allow to determine the optimal regimes of oxidation to obtain needed photonic device properties.
Optical contrastivity of complicated materials: finite layered structures
Abstract
We define the intrinsic optical contrastivity of a complicated layered
structure as the relative total gap taken inside the total
internal reflection region over a chosen range of frequencies. The notion
introduced for ordered 1D systems retains its meaning for 2D and 3D ordered optical
systems, as well as for disordered structures. The parametric maps of contrastivity and
sensitivity are calculated for 1D comb matrices based on glass, silicon, and microporous
silicon with various fillings, comb sizes, and densities of a gaseous filling. The
existence of areas on a parametric map which are highly sensitive to deviations in the
contrastivity is shown for different materials. In the case of a gaseous filling of voids
between the matrix material layers, the areas of a very high sensitivity are also found.

AXIOMATISABILITY OF WEAKLY FLAT, FLAT, AND PROJECTIVE S-ACTS
ABSTRACT This paper gives necessary and sufficient conditions on a monoid S that the class of flat left S-acts be (first order) axiomatisable. It presents also a streamlined version of the result of Stepanova that the class of projective left S-acts is axiomatisable if and only if the strongly flat left S-acts are axiomatisable and S is left perfect.