Baruch Fischer

Coherent oscillation by self‐induced gratings in the photorefractive crystal BaTiO3

We report here the demonstration of several new optical oscillator configurations including a unidirectional ring oscillator and a self‐pumped phase conjugate mirror. The gain medium is BaTiO3, pumped by a 632.8‐nm He‐Ne laser at power levels down to 50 μW.

Amplified reflection, transmission, and self-oscillation in real-time holography

A theory of phase conjugation in asymmetric materials that allow a phase shift between the grating and the light-interference pattern is developed. We find that when this phase is nonzero, maximum phase-conjugate reflectivity occurs for unequal pump intensities. The conditions for self-oscillation are studied.

Exact solution of a nonlinear model of four-wave mixing and phase conjugation

An exact solution of a nonlinear model of holographic four-wave mixing is derived. An expression for the reflectivity of a phase-conjugate mirror with depleted pumps is presented. We find that such a phase-conjugate mirror may exhibit bistability.

Passive phase conjugate mirror based on self‐induced oscillation in an optical ring cavity

A passive phase conjugate mirror based on four-wave mixing in an optical ring cavity is described. Unlike previously demonstrated passive phase conjugate mirrors it generates only one of its pumping beams by nonlinear optical interactions, the other being provided by feedback of the probe after transmission through the nonlinear medium. The results of a theory yielding phase conjugate reflectivity and oscillation thresholds are presented together with an experimental demonstration of phase conjugation in barium titanate and strontium barium niobate. The device is self-starting by four-wave mixing, and has an oscillation threshold lower than that of other previously demonstrated passive phase conjugate mirrors with similar ease of alignment. The operation of a device which generates nonconjugate oscillation beams is also reported.

Passive (self-pumped) phase conjugate mirror: Theoretical and experimental investigation

We report the results of a theoretical and experimental investigation of a passive (self-pumped) phase conjugate mirror. This device is based on real time holography in materials which allow a spatial phase shift between the refractive index grating and the light interference pattern. An imaging experiment is reported showing the phase conjugating nature of the device. The holographic medium used was a single crystal of barium titanate.

Amplifying continuous wave phase conjugate mirror with strontium barium niobate

We report the use of Sr1−x Bax Nb2O6 as an efficient holographic four‐wave mixing medium. We have used this material in a continuous wave phase conjugate mirror with reflectivity exceeding unity, and in a phase conjugate resonator.

Laser with dynamic holographic intracavity distortion correction capability

We report here a novel laser resonator with the ability to correct for intracavity phase distortions. The optical cavity employs a passive (self-pumped) phase conjugate reflector to provide this capability.

Real‐time phase conjugate window for one‐way optical field imaging through a distortion

We demonstrate one‐way optical field imaging through a distorting medium using a four‐wave mixing implementation of real‐time holography. Information can be transmitted at an arbitrarily fast rate as long as the mixing medium can respond to changes in the distortion.

Phase of phase conjugation and its effect in the double phase-conjugate resonator

Expressions for the phase of reflection from a photorefractive phase-conjugate mirror are obtained as a function of the intensity and phase of the pump and the probe beams. The phase is independent of these parameters in common photorefractive conditions in which the index grating is spatially shifted 90 degrees with respect to the light-interference pattern. Multiple solutions exist for the phase and intensity of the reflection at large coupling strength. Oscillation conditions involving frequency detuning are obtained for the double phase-conjugate resonator (resonator formed with two phase-conjugate mirrors).

Achromatic double phase conjugate mirror

Abstract We show that the double phase conjugate mirror may be made achromatic by using material dispersion to compensate the dispersion of the photorefractive grating. It is shown that the bandwidth of the entire visible spectrum may be accommodated in barium titanate crystal. The achromatic conditions found in the experiment are in good agreement with theory. Broadband to single frequency image conversion is demonstrated.