Phase conjugation

About: Phase conjugation is a research topic. Over the lifetime, 3694 publications have been published within this topic receiving 49099 citations.

Supercritical parametric phase conjugation of ultrasound. Numerical simulation of nonlinear and nonstationary mode

Abstract: This paper investigates the saturation mechanism of the nonstationary supercritical mode of parametric wave phase conjugation in a magnetostrictive medium The numerical simulation considers the two most probable nonlinear mechanisms of interaction between elastic deformation and electromagnetic excitation For the qualitative study of the dynamics of the system, a one-dimensional numerical simulation is sufficient if applied to an infinite medium with a finite active zone The temporal form of the conjugate wave is obtained for both hypotheses Comparison with experiments shows that only one mechanism corresponds to the experimental behavior

Phase-conjugation Broad Area Twin-contact Semiconductor Laser

Abstract: Experimental demonstration of lasing in a broad area twin-contact semiconductor laser which operates as a phase-conjugation (PC) mirror in an external cavity configuration is reported. This allows “self-aligned” and self-pumped spatially nondegenerate four-wave mixing to be achieved without the need for external optical signals. The external cavity laser system is very insensitive to tilt misalignments of the external mirror in the PC regime and exhibits very good mechanical stability. The resonant frequency of the external cavity lies in the GHz range which corresponds to a subnanosecond time response of phase conjugation processes in the semiconductor laser.

Time-dependent phase conjugation and four-wave mixing in plasmas

Abstract: Time‐dependent four‐wave mixing and phase conjugation in plasmas are treated, taking into account resonant longitudinal plasma modes and effects of spatial nonuniformity. A space‐time formulation of four‐wave processes in the ponderomotive force regime yields linearized equations, which are solved analytically as a combined initial/boundary‐value problem in slab and inhomogeneous geometries. The plasma response is incorporated in a ‘‘grating’’ Green’s function, expressed in terms of linear quasilongitudinal susceptibilities. Response times, decay times, and absolute instabilities are treated analytically. Plasma nonuniformity can speed up the response of the conjugate wave and modify resonant absolute instability thresholds. A new class of resonant absolute instabilities occurs when the counterpropagating pump waves have unequal intensities. The thresholds can be rather low for pump waves of modest intensity, provided the resonant grating has a long lifetime. Below these thresholds, regimes of stable amplification of the phase‐conjugate wave relative to the incident signal are possible with pumps of unequal intensity.

Unified method for solution of wave equations in photorefractive media

Abstract: A unified but simple method for solution of four-wave mixing equations in photorefractive crystals in both transmission and reflection geometries is presented. The method is applied to the problems of double phase conjugation and two-wave mixing with crossed polarizations in cubic crystals.

Optical phase conjugation in dyes embedded in polymer films

Abstract: Studies on low power optical phase conjugation (OPC) in three saturable dyes, viz., eosin, erythrosin B, and rose bengal, embedded in two polymer films, viz., gelatin and polyvinyl alcohol, are presented. Experiments are performed using the 514.5 nm line of an argon-ion laser. Saturation intensities are determined from the transmission versus intensity plots, and triplet lifetimes are estimated from the phosphorescence decay curves. OPC experiments are performed, and the variation of OPC reflectivity with intensity and absorption length is studied. Experimental results are compared with the theory of degenerate four-wave mixing in absorbing media proposed by R. L. Abrams and R. C. Lind [Opt. Lett. 2(4), 94 (1 978)]. There is fair agreement between the theory and the experimental observations. The limitations in using these films for cw OPC applications are briefly discussed.