Impact of Earth's gravity on Gaussian beam propagation in hemispherical cavities

TL;DR

This paper theoretically examines how Earth's gravity influences Gaussian beam propagation in hemispherical optical cavities, revealing phase shifts and beam bending effects that impact cavity calibration and laser stabilization.

Contribution

It introduces a model for Gaussian beam behavior under Earth's gravity in hemispherical cavities, highlighting gravitationally induced phase shifts and beam deviations.

Findings

Gravity causes downward bending of the beam.

Phase shifts depend on cavity parameters.

Implications for cavity calibration techniques.

Abstract

We theoretically investigate the influence of gravity on laser light in a hemispherical optical cavity, operating on Earth. The propagation of light in such a cavity is modeled by a Gaussian beam, affected by the Earth's gravitational field. On laboratory scale, this field is described by the spacetime of homogeneous gravity, known as Rindler spacetime. In that spacetime, the beam is bent downwards and acquires a height dependent phase shift. As a consequence the phase fronts of the laser light differ from those of a usual Gaussian beam. Assuming that the initial beam enters the cavity along its symmetry axis, these gravitational effects cause variations of the beam phase with every cavity round trip. Detailed calculations are performed to investigate how these phase variations depend on the beam parameters and the cavity setup. Moreover, we discuss the implications of our findings for cavity calibration techniques and cavity-based laser stabilization procedures.