On speed of a photon in a dispersing medium

TL;DR

This paper proposes a model showing that in dispersive media with refractive index greater than one, photons propagate at the phase velocity, explaining experimental results and the absence of superluminal effects.

Contribution

The paper introduces a model linking photon speed in dispersive media to phase velocity, supported by experimental data and detailed dispersion calculations.

Findings

Photon velocity in dispersive media equals phase velocity.

Refractive index greater than unity causes Cherenkov radiation.

No superluminal propagation observed in the studied conditions.

Abstract

On speed of a photon in a dispersing medium Ogluzdin Valeriy E. Abstract Based on the author of the experimental results and their treatment, a model that demonstrates that the real dispersive medium in spectral regions where the refractive index greater than unity, the velocity of propagation of photons in this environment corresponds to the phase velocity of light. These portions of the spectrum (for example, atomic potassium vapor or other alkali metal) are from low-frequency side of the main lines of the doublet and are available for research using tunable lasers. In the calculations took into account the fact that the atomic vapor of alkali metal used as a dispersing medium, in accordance with the theory of dispersion in the above sections of the spectrum, on the periphery of the cross section of laser beam with Gaussian intensity distribution across the beam - in the shadows refractive index n ({\nu}) is greater than unity, and the axis of the beam, where the radiation intensity is maximum - for radiation following the leading edge of the light pulse, the refractive index is unity, which ensures smooth on the beam axis, without any delay "superluminal "propagation of light with velocity c. This fact causes the appearance of the shadow cone of Vavilov - Cherenkov radiation, indicating a slow propagation of photons from the source of the cone with phase velocity c / n ({\nu}).