Random-Access, Page-Oriented, Stimulated Echo Optical Cache Memory

摘要

This report describes a program of research to develop an innovative high-speedrandom-access optical cache memory. This innovation is based on a novel approach using time-domain-stimulated echo storage in smaller independent-frequency bins comprising the larger absorption bandwidth of rare-earth-doped crystals. The advantages of the approach are that memory can be stored in space, time, and frequency domain, allowing the tailoring of a flexible memory architecture to match those of the computational processor. We have instigated frequency, time, and space domain storage using a single frequency dye laser as an excitation source of optical pulses. Using Eu3+ doped Y2SiO5 crystal, we have stored and retrieved a 1.6 Kbit data stream, 40-microns long at a data rate of 40 Mbits/s in a single-frequency channel at one spatial location. By multiplying the total frequency channels available (at a single spatial spot of approx. 32), we infer a storage capacity of greater than approx. 5 x 10(4) bits per spatial spot, which is close to the theoretical storage density of 5 x 10(6) bits per spatial spot. We have achieved these results by solving the coherent saturation problem, caused by the limited frequency content of the data train, by using the pseudo-random biphase modulation technique. Our results have demonstrated for the first time that the stimulated echo memory and, in particular, the time-frequency hybrid memory, is the memory of choice for the next generation of optical random access memory.