Optical interferometry between image-bearing beams and their redirected phase conjugates

We present three new interferometers, which are based on interference between combinations of image-bearing optical fields and their redirected phase-conjugate reflections in two- and three-dimensional configurations. Our interferometers can be used to implement mathematical operations on images, including the Hartley transform

Phase conjugation involving incoherent counterpropagating beams in photorefractive media

We propose and analyze a new type of phase conjugation between counterpropagating beams in photorefractive materials based on diffraction from transmission gratings only. This effect does not require temporal coherence between the counterpropagating beams and may occur spontaneously, with no external seeding, even with wide (frequency) band light sources

Intersubband-transition-induced phase matching

We suggest the use of the refractive-index changes associated with the intersubband transitions in quantum wells for phase matching in nonlinear materials. An improvement in the conversion efficiency of mid-IR second-harmonic generation by almost 2 orders of magnitude over non-phase-matched bulk GaAs is predicted. We also show that the linear phase contributions of intersubband transitions used for resonant enhancement of second-harmonic generation must be considered, as they could limit the conversion efficiency by increasing the phase mismatch on one hand or offset the bulk's dispersion and lead to phase matching on the other

Nonlinear wave dynamics in honeycomb lattices

We study the nonlinear dynamics of wave packets in honeycomb lattices, and show that, in quasi-1D configurations, the waves propagating in the lattice can be separated into left-moving and right-moving waves, and any wave packet composed of left (or right) movers only does not change its intensity structure in spite of the nonlinear evolution of its phase. We show that the propagation of a general wave packet can be described, within a good approximation, as a superposition of left and right moving self-similar (nonlinear) solutions. Finally, we find that Klein tunneling is not suppressed due to nonlinearity

Limitation on holographic storage in photorefractive waveguides

We show that photorefractive waveguide devices are subject to a limitation on their holographic storage capability owing to transversely nonuniform nonlinear losses to evanescent and radiation modes

Wavelength-multiplexed computer-generated volume holography

We demonstrate recording and reconstruction of multiple-computer-generated wavelength-multiplexed volume holograms in a holographic storage medium. The holograms display high selectivity, and their reconstruction process results in a convenient conversion of wavelength into angular multiplexing

Interferometric electro-optical signal processors with partially coherent illumination

Fourier- and Hartley-related transforms are realized in a family of interferometers. The implementation of these interferometers as image correlators is investigated theoretically and experimentally with both coherent and spatially incoherent illumination. Several correlators that can be used for pattern recognition are studied and demonstrated experimentally as special cases

Nonlinear self-phase matching of optical second harmonic generation in lithium niobate

We show that the nonlinear index perturbation due to light-induced photovoltaic space-charge field in LiNbO3 can give rise to self-phase matching of second harmonic generation. Increase of the conversion efficiency is accompanied by formation of stationary and nonstationary patterns in the spatial structure of the generated second harmonic. The space-charge field can be induced either by the initially non-phase-matched second harmonic or by an external seed

Temporal evolution of photorefractive double phase-conjugate mirrors

We present wave-optics calculations of the temporal and spatial evolution from random noise of a double phase-conjugate mirror in photorefractive media that show its image exchange and phase-reversal properties. The calculations show that for values of coupling coefficient times length greater than two the process exhibits excellent conjugation fidelity, behaves as an oscillator, and continues to operate even when the noise required for starting it is set to zero. For values less than two, the double phase-conjugation process exhibits poor fidelity and disappears when the noise is set to zero

Breakdown of Dirac Dynamics in Honeycomb Lattices due to Nonlinear Interactions

We study the dynamics of coherent waves in nonlinear honeycomb lattices and show that nonlinearity breaks down the Dirac dynamics. As an example, we demonstrate that even a weak nonlinearity has major qualitative effects one of the hallmarks of honeycomb lattices: conical diffraction. Under linear conditions, a circular input wave-packet associated with the Dirac point evolves into a ring, but even a weak nonlinearity alters the evolution such that the emerging beam possesses triangular symmetry, and populates Bloch modes outside of the Dirac cone region. Our results are presented in the context of optics, but we propose a scheme to observe equivalent phenomena in Bose-Einstein condensates