Black hole optical analogue: photon sphere microlasers

TL;DR

This study creates a laboratory analogue of black hole photon spheres using 2D optical surfaces, enabling the observation of quasinormal modes and photon sphere lasing in a controlled setting.

Contribution

It introduces a novel optical analogue of black hole photon spheres with analytical and experimental demonstration of confined modes and lasing at the photon sphere.

Findings

Analytical computation of optical quasinormal modes confined around the photon sphere.

Experimental demonstration of lasing at the photon sphere using 3D-printed microcavities.

Mode profiles match analytical predictions, validating the analogue model.

Abstract

The bell-like ringdown of the gravitational field in the last stage of the merging of massive black holes is now routinely detected on earth by the last generation of gravitational wave detectors. Its spectrum is interpreted as a sum of damped sinusoidal vibrations of the spacetime in the vicinity of the black hole. These so-called quasinormal modes are currently the subject of extensive studies, yet, their true nature remains elusive. Here, we emulate, in the laboratory, genuine four-dimension black hole metrics by two-dimensional optical curved surfaces that preserve the features of lightlike geodesics. %We establish the analogy with gravitational waves radiated by relaxing black holes, and We analytically compute the optical quasinormal modes and show that they are confined around the photon sphere, the unstable region around a black hole where spacetime curvature traps light in circular orbits. By 3D-printing non-Euclidean dye-doped microcavities, we demonstrate lasing at the photon sphere with a mode profile that closely matches the analytical prediction. These results paves the way for observing astrophysical phenomena in tabletop setups and is likely to inspire innovative designs in photonics.