Slow light, fast computers

David R. Selviah

Guang S. He

Fast or slow light propagation means that the group velocity of a quasi-monochromatic light pulse propagating in a resonant medium can be significantly faster or slower than the light speed in a vacuum. Since the end of the last century and the beginning of this century, studies on this subject have attracted a great deal of interest. Remarkable progress has been achieved, based on various nonlinear optical interactions in resonant media. The fundamental research on this subject can enrich our understanding of special relativity and causality in physics. On the other hand, those mechanisms and techniques developed for fast and slow light propagation have provided the potential for many future applications, such as optical buffers and variable delay lines for optical networks, optical computing, optical telecommunications, optical data storage, and signal processing.

M. Mitchell Waldrop

Bin Luo, Hong Mei Guo

Dispersion properties of an optical medium can be greatly changed using electromagnetically induced transparency (EIT) and other nonlinear effects. Thus, the group velocity of light pulse can be much smaller (greater or even negative) than light speed in vacuum, which is called slow (fast) light. Slow and fast light are very useful in optical processing, such as optical buffer, switching, and storage devices. Usually, slow and fast light cannot be generated simultaneously in the same medium. In this paper, we propose applicable level structures to generate controllable slow and fast light simultaneously at two frequencies, with the same polarization.

W. Wayt Gibbs

Tianqi Xu, Shaonan Zheng, Yang Qiu +5 more

Tunable slow and fast light generation in a silicon-on-insulator (SOI) Fano resonator is proposed and experimentally demonstrated. The slow and fast light generation with symmetric and asymmetric coupling conditions of the Fano resonator is theoretically analyzed. Under a slightly imbalanced coupling condition, the two output ports of the Fano resonator could produce a fast light and a slow light, respectively. By utilizing the thermo-optic (TO) effect to change the phase difference of the two optical beams coupled into the resonator, the transition of fast and slow light can be realized at the fixed resonance wavelength. Experimental results show that a slow-to-fast transition (group delay from 0.852 to -1.057 ns) at one resonance wavelength, and a fast-to-slow transition (group delay from -0.22 to 0.867 ns) at another resonance wavelength are realized simultaneously by controlling the microheater to tune the phase difference.