Black-Hole Ringdown on an Optical Table: Photon-Sphere Modes in Curved Microlasers

Black-hole mergers emit gravitational waves whose final stage, the ringdown, carries the characteristic signature of the newly formed black hole. This signal is interpreted in terms of quasinormal modes, damped vibrations closely associated with the photon sphere.

The seminar will begin with an introduction by Ofek Birnholtz, who will present the astrophysical setting: black holes, photon spheres, gravitational waves from compact-object collisions, ringdown, and quasinormal modes.

Patrick Sebbah will then show how these ideas can be brought to the optical table using curved microcavities. In this optical analogue, the curvature of space is engineered to support modes localized near the photon sphere, distinct from conventional whispering-gallery modes. The seminar will present the observation of these photon-sphere modes in three-dimensional microlasers and briefly discuss how the same concept extends to elastic waves.