Dynamic volume holography and optical information processing by Raman scattering

Abstract

A method of producing holograms of three-dimensional (3D) optical pulses is proposed. It is shown that both the amplitude and the phase profile of 3D optical pulse can be stored in dynamic perturbations of a Raman medium, such as plasma. By employing Raman scattering in a nonlinear medium, information carried by a laser pulse can be captured in the form of a slowly propagating low-frequency wave that persists for a time large compared with the pulse duration. If such a hologram is then probed with a short laser pulse, the information stored in the medium can be retrieved in a second scattered electromagnetic wave. The recording and retrieving processes can conserve robustly the pulse shape, thus enabling the recording and retrieving with fidelity of information stored in optical signals. While storing or reading the pulse structure, the optical information can be processed as an analog or digital signal, which allows simultaneous transformation of 3D continuous images or computing discrete arrays of binary data. By adjusting the phase fronts of the reference pulses, one can also perform focusing, redirecting, and other types of transformation of the output pulses.

Cross talk-free coherent multi-wavelength Brillouin interaction

“…The theory of acousto-optic light storage in the situation where the data pulses have multiple wavelengths can be obtained by adapting the three-wave interaction model of Dodin and Fisch [20]. We consider the situation where an acoustic wave has the potential to couple to two optical data pulses: one which is perfectly phase-matched to the acoustic mode, while the second is offset by a frequency ∆F and so is phase-mismatched by ∆q (Eq.…”

“…We assume that the frequency shift associated with the Brillouin process is sufficiently small that the frequencies of the control and data pulses can be taken to be identical, although their difference in phase is non-negligible. Following [20], we move to a dimensionless coordinate system that co-propagates with the control pulse, such that…”

“…Before determining these parameters, we first make the approximation that the control pulse is both short enough in duration and sufficiently strong that the the interaction is "static" in the sense that all derivatives with respect to τ are small with respect to the derivatives with respect to ζ. This assumption holds provided |a 2 /L r | >> |ωQa 1 b/P | for the peak amplitudes [20], where L r is the pulse length of the read pulse. The static approximation states that the temporal variations of the acoustic and data pulses are small compared to the spatial derivatives in the moving reference frame of the write/read pulses.…”

Multiplexed image storage by electromagnetically induced transparency in a solid

“…The latter exhibit probably the most powerful conventional approaches for high-capacity optical memories [7]. However, in classical holography it is not possible to store the temporal shape of a pulse (or sequences of pulses) [8], that is, information spread in the time domain. To overcome this drawback, time-domain frequencyselective optical data storage techniques were proposed [9].…”