Topological Reflections Revisited

Use of a Two-Channel Moiré Wavefront Sensor for Measuring Topological Charge Sign of the Vortex Beam and Investigation of Its Change Due to an Odd Number of Reflections

One of the solutions of the Helmholtz equation is the vortex beams. In the recent decades, production and applications of these types of beams have found serious attentions. Determination of the vortex beam topological charge and its sign are very important issues. Odd number of reflections of the vortex beam changes its vorticity. In this paper, we have used a q-plate to generate a vortex beam...

Compactness in constructive analysis revisited

In [5], [3] we have developed a unified Type 2 theory of computability and continuity and a theory of representations. In a third paper [6] representations useful for a new kind of constructive analysis were presented. As an application of these concepts we shall now consider constructive compactness. We introduce 'reasonable' representations of closed and compact sets and prove two different v...

A topological characterization of ordinals: van Dalen and Wattel revisited

We revisit van Dalen and Wattel’s characterization of linearly ordered topological spaces in terms of nests of open sets and use this to give a topological characterization of ordinals. In particular we characterize !1.

Gate-tunable supercurrent and multiple Andreev reflections in a superconductor-topological insulator nanoribbon-superconductor hybrid device

Maker fringes revisited: second-harmonic generation from birefringent or absorbing materials

We present a new formulation of Maker fringes in parallel-surface films, using self-consistent boundary conditions for reflections and allowing for any degree of refractive-index dispersion. This treatment of the second-harmonic reflections and dispersion, unlike a number of previous derivations, leads correctly to the expected form for the effective second-harmonic d coefficients. Complete exp...