Deducing radiation pressure on a submerged mirror from the Doppler shift

TL;DR

This paper proposes an experimental method to measure radiation pressure on a submerged mirror by analyzing Doppler shifts, revealing how it varies with phase angle and bridging the Abraham and Minkowski momentum frameworks.

Contribution

It introduces a simple experimental setup to determine the radiation pressure on a submerged mirror by measuring Doppler shifts and phase changes, connecting theoretical momentum values.

Findings

Radiation pressure depends on phase angle psi_0 of the reflection coefficient.

The momentum per photon ranges between Abraham and Minkowski values.

A proposed experiment can accurately deduce radiation pressure from Doppler shift measurements.

Abstract

Radiation pressure on a flat mirror submerged in a transparent liquid, depends not only on the refractive index n of the liquid, but also on the phase angle psi_0 of the Fresnel reflection coefficient of the mirror, which could be anywhere between 0^{\circ} and 180^{\circ}. Depending on the value of psi_0, the momentum per incident photon picked up by the mirror covers the range between the Abraham and Minkowski values, i.e., the interval (2\hbarw_0/nc,2n\hbarw_0/c). Here \hbar is the reduced Planck constant, w_0 is the frequency of the incident photon, and c is the speed of light in vacuum. We argue that a simple experimental setup involving a dielectric slab of refractive index n, a vibrating mirror placed a short distance behind the slab, a collimated, monochromatic light beam illuminating the mirror through the slab, and an interferometer to measure the phase of the reflected beam, is all that is needed to deduce the precise magnitude of the radiation pressure on a submerged mirror. In the proposed experiment, the transparent slab plays the role of the submerging liquid (even though it remains detached from the mirror at all times), and the adjustable gap between the mirror and the slab simulates the variable phase-angle psi_0. The phase of the reflected beam, measured as a function of time during one oscillation period of the mirror, then provides the information needed to determine the gap-dependence of the reflected beam's Doppler shift and, consequently, the radiation pressure experienced by the mirror.