Fast- and slow-light-enhanced light drag in a moving microcavity

Fizeau’s experiment, inspiring Einstein’s special theory of relativity, reveals a small dragging effect acting on light inside a moving medium. Dispersion can enhance such light drag according to Lorentz’s predication. Here fast- and slow-light-enhanced light drag is demonstrated experimentally in a moving optical microcavity through stimulated Brillouin scattering induced transparency and absorption. The strong dispersion provides an enhancement factor up to ~104, greatly reducing the system size down to the micrometer range. These results may offer a unique platform for a compact, integrated solution to motion sensing and ultrafast signal processing applications. In accordance with the relativistic addition of velocities, the Fizeau experiment shows the dragging of light inside a moving medium which can be enhanced in dispersive medium. Here a strong dispersion, induced by stimulated Brillouin scattering, is shown to significantly enhance the light drag effect in a moving optical microcavity.