Polarization properties of photon Bose-Einstein condensates

TL;DR

This paper experimentally studies the polarization behavior of photon Bose-Einstein condensates, revealing how pump polarization influences condensate polarization and the limits of polarization degree.

Contribution

It provides the first detailed experimental analysis of polarization properties in photon Bose-Einstein condensates, confirming theoretical predictions and exploring polarization control.

Findings

Polarization strength increases above the condensation threshold.

Full linear polarization is achievable with specific pump polarization.

Polarization is limited to about 90% due to orthogonal state occupation.

Abstract

The first experimental realization of a photon Bose-Einstein condensate was demonstrated more than a decade ago. However, the polarization of the condensate has not been fully understood and measured in this weakly driven-dissipative system. In this letter, we experimentally investigate the polarization of thermal and condensed light depending on the power and polarization of the pump beam. With full control over the polarization of the pump, it is possible to create arbitrary states on the surface of the Poincar\'e sphere. We show that, in agreement with previous theoretical work, there is a remarkable increase in the polarization strength of the condensate above the threshold for a fully linearly polarized pump. Above a certain threshold also the degenerate orthogonal polarized state of the cavity is occupied, limiting the degree of polarization to approximately 90%.