Spectral and laser characteristics of a mirror with a corrugated waveguide on its surface

Abstract

To understand the origin of Solar Energetic Particles (SEPs), we must study their injection time relative to other solar eruption manifestations. Traditionally the injection time is determined using the Velocity Dispersion Analysis (VDA) where a linear fit of the observed event onset times at 1 AU to the inverse velocities of SEPs is used to derive the injection time and path length of the first-arriving particles. VDA does not, however, take into account that the particles that produce a statistically observable onset at 1 AU have scattered in the interplanetary space. We use Monte Carlo test particle simulations of energetic protons to study the effect of particle scattering on the observable SEP event onset above pre-event background, and consequently on VDA results. We find that the VDA results are sensitive to the properties of the pre-event and event particle spectra as well as SEP injection and scattering parameters. In particular, a VDA-obtained path length that is close to the nominal Parker spiral length does not imply that the VDA injection time is correct. We study the delay to the observed onset caused by scattering of the particles and derive a simple estimate for the delay time by using the rate of intensity increase at the SEP onset as a parameter. We apply the correction to a magnetically well-connected SEP event of 2000 June 10, and show it to improve both the path length and injection time estimates, while also increasing the error limits to better reflect the inherent uncertainties of VDA.

Recent Advances in Resonant Waveguide Gratings

“…Sychugov and Tishchenko demonstrated the TE to TM polarization conversion of light using conical (non‐collinear) incidence orientation . Gobulenko and Avrutsky observed the same resonances using a thin deposited ZnO‐corrugated waveguide, achieving much narrower reflection wavelength band in zero‐order configuration, thanks to a much lower refractive index contrast of the waveguide. After having studied the first diffracted order resonant anomalies of a multiple dielectric layer coated aluminum diffraction grating, Mashev and Popov demonstrated experimentally similar results with a corrugated waveguide manufactured by ions exchanged from molten AgNO 3 .…”

Optimization of the strength of a graded-index slab waveguide grating

“…A large α is necessary for instance for limiting the coupling length of the input/output grating coupler of a biosensor [1], for achieving resonant reflection of a narrow laser beam [2], for broadening the spectral acceptance of a grating coupler. Setting a waveguide at the condition for maximum α also permits to use the shallowest etching depth for a desired α value, thus to ease the etching process and to limit the resulting scattering.…”

Circular grating waveguide structures for intracavity generation of azimuthal polarization in a thin-disk laser

“…The polarizing principle is based on the coupling of the incident free-space wave to a true guided or leaky mode of the multilayer. In the first case, the coupling is accompanied by constructive interferences [12][13][14] that lead to a resonance peak in the reflectivity spectrum of the desired polarization, whereas in the second approach, it is accompanied by power leakage into the substrate of the mirror [6,7].…”