We observed superluminal Gaussian light pulse propagation in a Bi<sub>12</sub>SiO<sub>20</sub> crystal at room temperature by use of the dispersive phase coupling in the photorefractive two-wave mixing process. A negative group velocity of -2.6 m/s was achieved. The group velocity of the light pulse was able to be modified to quite a large extent by means of modification of the experimental conditions such as the total intensity of the two coupling beams.

© 2005 Optical Society of America

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