Spectral programming of temporal pulse sequences using photon echoes

Abstract

Optical memories based on spectral hole burning (SHB) and stimulated photon echoes (SPE) are attracting much attention. Both approaches add an extra dimension for addressing (frequency and temporal dimension respectively) to the spatial dimensions. With these concepts the storage density can become 103 – 106 times higher than in conventional optical memories. In both approaches, the ratio of the inhomogeneous line width to the homogeneous line width of the ions activated in the storage process determines the improvement in storage density. Compared to the SHB approach, SPE has certain advantages including high R/W rate and ability to process the stored (spatial as well we temporal) information. Using SPE, the authors have experimentally realised the AND, OR and NOT logical operations [1,2]. Further all optical processing, such as temporal pattern recognition, can be done using SPE.