Time-domain optical memories

Time-domain optical memories281 have been proposed also, by a combination of photon echo and PHB materials. If one uses a PHB material in the photon echo system, it is possible to preserve the population of electronic density of states in the guest molecules produced by a successive irradiation of two pulses. Thus one could read-out data again, even after a long time, by irradiation with a third pulse and observing the echo pulse. Time-domain optical memories have some clear advantages, as they offer the possibility of very fast multiple recording combined with simultaneous read-out and calculation capability. 

All methods mentioned in Table 1 operate (typically) in the frequency domain a monochromatic optical wave is usually considered. Two basically different groups of modeling methods are currently used methods operating in the time domain, and those operating in the spectral domain. The transition between these two domains is generally mediated by the Fourier transform. The time-domain methods became very popular within last years because of their inherent simplicity and generality and due to vast increase in both the processor speed and the memory size of modem computers. The same computer code can be often used to solve many problems with rather... 

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