Observation of Backward Pulse Propagation Through a Medium with a Negative Group Velocity

• DOI: 10.1126/science.1124524
• Publication Date: 2006-05-12T01:36:40Z
• Authors: George M. Gehring; Aaron Schweinsberg; Christopher Barsi; Natalie Kostinski; Robert W. Boyd
• Keywords: Group velocity

The nature of pulse propagation through a material with negative value the group velocity has been mysterious, as simple models seem to predict that pulses will propagate "backward" such material. Using an erbium-doped optical fiber and measuring time evolution intensity at many points within fiber, we demonstrate peak does backward inside even though energy flow is always in forward direction.