A method to achieve an extremely wide and flexible control of the group velocity in an optical fiber using stimulated Brillouin scattering is presented. Group velocities below 71,000 km/s on one hand, well exceeding the speed of light in vacuum on the other hand and even negative group velocities can readily be obtained
Tobias Kippenberg, Maxim Karpov, Hao Song, Xinzhou Su
Dirk Grundler, Thomas Yu, Heena Yang, Joyeeta Sinha