Recent progresses towards distance-limitless superluminal propagation based on stimulated Brillouin scattering have
been presented. By suppressing multiple-longitudinal-mode lasing oscillation, Brillouin-induced superluminal
propagation through hundreds-of-meter optical fibers can be successfully achieved.
Long distance superluminal propagation in optical fibers via cascaded Brillouin lasing oscillation is proposed and experimentally demonstrated. The Gaussian pulses experience negative group-velocity superluminal propagation with the advancement of ~300ns in 20-m single mode fiber.
Negative group velocity superluminal propagation has been experimentally investigated based on stimulated Brillouin scattering in a 10-m highly nonlinear fiber (HNLF) ring cavity. The advancement of 365.8 ns with a high average slope efficiency of 118.9 ns/mw versus the output lasing power was observed. The maximum negative group velocity of −0.105c and the minimum group index of −9.499 have been achieved by using the HNLF with high Brillouin gain coefficient and the optimized 1/99 coupler ratio in the cavity. The tunability of negative group velocity and group index can be easily controlled by the input pump power and optical coupler ratio indicating potential applications for a highly advanced sensing scheme based on Brillouin oscillation superluminal propagation.