Ultra-slow and superluminal light propagation in solids at room temperature

Slow and superluminal group velocities can be observed in any material that has large normal or anomalous dispersion. While this fact has been known for more than a century, recent experiments have shown that the dispersion can be very large without dramatically deforming a pulse. As a result, the significance and nature of pulse velocity is being re-evaluated. In this thesis, I review some of the current techniques used for generating ultra-slow, superluminal, and even stopped light. While ultra-slow and superluminal group velocities have been observed in complicated systems, from an applications point of view it is highly desirable to be able to do this in a solid that can operate at room temperature. I describe how coherent population oscillations can produce ultra-slow and superluminal light under these conditions. In addition, I explore the information (or signal) velocity of a pulse in a material with large dispersion. Next, I am able to demonstrate precise control of the pulse velocity in an erbium-doped fiber amplifier. I extend this work to study slow light in an SBS fiber amplifier. This system has much larger bandwidth and can produce much longer fractional delays, and therefore has great potential to control the group velocity for applications in all-optical delay lines. Finally, I investigate numerically and experimentally the stability of ring-shaped beams with orbital angular momentum in a material with a saturable nonlinearity.