In this paper, we study the novel propagation properties of an improved triangular-type air-core photonic bandgap fiber (PBGF) structured with an anti-resonant silica core surround, through a full-vector modal solver based on the finite-element method (FEM). At first, to realize a single-mode operation over a wide wavelength range, the fiber whose core is constructed by removing 1 air-hole and ...

in this paper we study the existence of commuting regular elements, verifying the notion left (right) commuting regular elements and its properties in the groupoid g(n) . also we show that g(n) contains commuting regular subsemigroup and give a necessary and sucient condition for the groupoid g(n) to be commuting regular.

We study the dependence of the retrieval parameters, such as the electric permittivity, e, the magnetic permeability, m, and the index of refraction, n, on the size of the unit cell of a periodic metamaterial. The convergence of the retrieved parameters on the number of the unit cells is also examined. We have concentrated our studies on the so-called fishnet structure, which is the most promis...