Optical buffers based on slow light in electromagnetically induced transparent media and coupled resonator structures: comparative analysis

Abstract

The optical buffer is a key component in all-optical information processing systems. Recently a number of schemes that use slow light propagation in various media and structures have been proposed as means toward implementation of all-optical buffers. We rigorously analyze the similarities and differences in approaches that use electromagnetically induced transparency (EIT) and coupled resonant structures (CRS). We introduce the figure of merit, finesse, that is common to both approaches and obtain fundamental limitations on bit rates and storage capacities of optical buffers. We show that at very low bit rates and storage capacities EIT outperforms CRS, but at rates of 10 Mbits/s and above the EIT medium becomes quite inefficient, and the situation is reversed. Two types of CRS based on high-index-contrast fiber gratings and high-index semiconductor-air photonic crystals and (or) microring resonators are found to hold promise for applications in the 1-1000-Gbits/s range, but only if the losses can be drastically reduced.