Diffraction Patterns of the Millimeter Wave with a Helical Wavefront by a Triangular Aperture

Abstract

In this paper, for the first time, we developed the measurement method of the Topological Charge (TC) in millimeter wave with helical wavefront by a triangular aperture. The millimeter wave with helical wavefront was passively generated by conversion from a Gaussian beam using a spiral mirror, which we also developed. Each diffraction pattern depended on TC, and negative TC and positive TC were symmetric pairs under reflection. These diffraction patterns were perfectly compatible with the calculation results.

Radiation of twisted photons in elliptical undulators

“…In the particular cases of circular and planar undulators, formula (33) reproduces formulas (54) of [9] and (3.7) of [10]. Furthermore, assuming that the quantum recoil is small and employing the paraxial approximation n 2 ⊥ ≪ 1, formula (33) turns into the expression (25). Using the symmetry property (38), it is not difficult to show that the sign flip of the chirality of the elliptic helix trajectory of the particle in the undulator results in the transformation rule (26) for the probability of radiation of twisted photons (33).…”

“…Moreover, the investigations of the radiation properties in the basis of twisted photons allow one to establish the properties that are difficult to unveil in the basis of plane-wave photons, which is commonly used to describe radiation. Currently, there are plenty of designs for detectors enabling one to register twisted photons, to find the number of them and their quantum numbers in the incident radiation [18][19][20][21][22][23][24][25][26][27]. Therefore, the expressions for the average number of twisted photons that are derived in the present paper can be directly verified in experiments.…”

Proposal for experimental observation of the twisted photons in transition and Vavilov-Cherenkov radiations

“…Such a detector of twisted photons operates in different spectral ranges. The experiments [31,32] show that the lens in this scheme can be removed without a large distortion of the diffraction pattern.…”

Propagation properties of electron cyclotron waves with helical wavefronts in magnetized plasma

“…A spiral-shaped mirror has been developed to generate an optical vortex with designed l in a frequency range of millimeter waves. 19 Thus, an optical vortex can be generated by installing the spiral-shaped mirror between a gyrotron and launching antenna mirrors in the existing transmission line. This enables verification of whether an optical vortex can be a tool to heat high-n e plasma.…”