Optical Echo-processors Research Articles

Change in Information Flow Density in Optical Echo Processors

We consider the change in information flow density in the stimulated photon-echo response in a threelevel system as a function of the spectrum nonequidistance parameter.

Determination of Optimum Conditions for Reproducing Information in Optical Echo Processors

We consider correlations between the temporal profile of stimulated photon echo and the temporal form of the object laser pulse. We find that the information measure is a good criterion in choosing optimum conditions for reproducing information in optical echo processors. We show that the reproducibility of information in the stimulated photon-echo response in this regime depends on the object-pulse area.

Information coding of exciting laser pulses in an optical echo-processor

We report the possibility of controlling the distribution of quantum bits within an inhomogeneously broadened line of a resonant transition in recording and transforming information in optical echo-processors. We consider the efficiency of realisation of the elementary logic XOR gate based on a two-pulse excitation of a resonant medium with phase memory. The encoded information is incorporated into the temporal shape of laser pulses in the form of amplitude modulation of an ‘echelon’ of present (‘1’) and absent (‘0’) pulse-codes for obtaining more efficient logic elements that reduce the noise in a quantum communication channel.

The Information Coding in the Time Structure of the Object of a Laser Pulse in an Optical Echo Processor

The encoding of information in time intervals of an echelon of laser pulses of an object pulse in the optical echo processor is considered. The measures of information are introduced to describe the transformation of classical information in quantum information. It is shown that in the description of information transformation into quantum information, the most appropriate measure is a measure of quantum information based on the algorithmic information theory.

Multichannel information processing in the optical echo-processors on the basis of Van-Fleck paramagnet crystals

The analysis of various modes of multichannel information recording and readout in conditions of a stimulated (accumulated and long-living) photon echo in the crystals doped with rare earth ions which are known as Van-Fleck paramagnets has been performed in order to utilize them in the operation of low-temperature optical echo-processors.

Coherent optical spectroscopy of promising materials for solid-state optical processors

State of the art of optical coherent spectroscopy of doped solids that are promising as information carriers for optical processors is reviewed. Special attention is paid to optical echo spectroscopy of doped crystals classified as the Van-Vleck paramagnets where the long-lived stimulated echo is observed with the optical-memory time reaching several hours at low temperatures. Modern elaborations of optical echo processors based on this echo phenomenon are discussed. Physical principles of femtosecond echo spectroscopy and coherent four-wave mixing spectroscopy are formulated. The abilities of these methods in the diagnostics of fast processes at room temperature are illustrated using examples of a doped polymer films. The results of elaborations of a new branch of optical spectroscopy (biphoton spectroscopy) are also presented. The advantages and possible applications of this method are demonstrated using an example of two crystals (Er3+:YAG and Cr3+:Al2O3).

Stimulated photon echo with temporal data coding in the Hopfield-Little regime

A model of an optical neural network with associative memory using stimulated photon echo (SPE) with temporal data coding is presented. The electrical field’s calculation of the SPE signals is carried out for case of multiple influences on the resonant medium by optical pulses. A computer model of an optical echo processor with associative retrieval of information is elaborated.

Multipulse excitation of photon echo and its application for developing the principle of design of an optical echo processor

A method for optical data processing, based on the mode of multipulse excitation of photon echo signals, has been proposed and applied to solution of the knapsack problem. In this case, along with the recognition of solvability, the solution itself is found in the optical processor. A scheme of a possible optical echo processor on molecular iodine vapor is presented.

Multipulse excitation of photon echo and its application for developing the principle of design of an optical echo processor

Multipulse excitation of photon echo and its application for developing the principle of design of an optical echo processor

The correlation of inhomogeneous broadening and the efficiency of data locking in optical echo processors

The formation of responses of stimulated photon echo and the efficiency of data locking under the action of a spatially inhomogeneous electric field on a resonance medium are analyzed. It is shown that the action of a spatially inhomogeneous electric field on a resonance medium between the first and second excitation laser pulses leads to the reversible destruction of the phase memory of the medium, which manifests itself in a change in the time-frequency correlation of inhomogeneous broadening. The possibility of controlling the efficiency of data locking by varying the gradient of an external nonuniform electric field is considered.

Principles of construction of optical echo processors

An analysis is made of the possibility of utilization of the photon echo effect in optical digital processing of discrete images by the method of control operators, which makes it possible to solve a number of problems. Different regimes for the excitation of the photon echo are in practice usable in all component parts of a processor, which makes this effect potentially promising for the use in optical data processing.