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

2006; American Association for the Advancement of Science; Volume: 312; Issue: 5775 Linguagem: Inglês

10.1126/science.1124524

1095-9203

George M. Gehring, Aaron Schweinsberg, Christopher Barsi, Natalie Kostinski, Robert W. Boyd,

Advanced Fiber Laser Technologies

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