Driven polariton condensate (blue-orange surface) trapped in an annular potential induced by a nonresonant optical pump (blue-red surface), with the location of optical vortices indicated by the dashed white and blue lines.

From the article:

Spontaneous Formation of Time-Periodic Vortex Cluster in Nonlinear Fluids of Light
Kirill A. Sitnik, Sergey Alyatkin, Julian D. Töpfer, Ivan Gnusov, Tamsin Cookson, Helgi Sigurdsson, and Pavlos G. Lagoudakis
Phys. Rev. Lett. 128, 237402 (2022)

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