Topic
Phase conjugation
About: Phase conjugation is a research topic. Over the lifetime, 3694 publications have been published within this topic receiving 49099 citations.
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TL;DR: In this article, an experimental investigation of enhanced backscattering (partial phase conjugation) for phase screens generated by a propane gas burner or a group of electric fan heaters is presented.
Abstract: We report an experimental investigation of enhanced backscattering (partial phase conjugation) for phase screens generated by a propane gas burner or a group of electric fan heaters. A 10-cm-diameter collimated laser beam is transmitted through the phase screen to a plane mirror and reflected back through the same screen. When the doubly scattered radiation is imaged at infinity, an intensity enhancement is observed in the backscattering direction. The backscattering peak can have a width close to the diffraction limit despite the large scattering that is due to the screens and to the relatively large astigmatism of the collimating mirror. The results are shown to be in good agreement with the theoretical predictions.
40 citations
TL;DR: The parameters which govern the effective interaction length at threshold for phase conjugation due to stimulated Brillouin scattering are investigated and the length is found to be the shorter of the following parameters: the cell length, 3 times the coherence length or 5 times the Rayleigh range of the input laser radiation.
Abstract: We have investigated experimentally the parameters which govern the effective interaction length at threshold for phase conjugation due to stimulated Brillouin scattering. We found the length to be the shorter of the following parameters: the cell length, 3 times the coherence length or 5 times the Rayleigh range of the input laser radiation. We have also found that the fidelity of the return depends strongly on the coherence length when this parameter is much shorter than the cell length. Results are also presented on fluctuations in fidelity at high power and long pulse lengths.
40 citations
TL;DR: It is experimentally demonstrate that three-excitation-pulse photon echo signals can be backward-propagating, phase-conjugate replicas of the second echo- Excitation pulse.
Abstract: We experimentally demonstrate that three-excitation-pulse (i.e., stimulated) photon echo signals can be backward-propagating, phase-conjugate replicas of the second echo-excitation pulse. Working on the 555.6-nm absorption line of atomic Yb vapor, echo signals, effectively 0.5% as intense as the second excitation pulse, are shown to reproduce image information carried by the second excitation pulse even when wave-front distorters are employed.
40 citations
TL;DR: In this article, a 20 kHz ac square-wave electric field was used to enhance the beam-coupling gain and the degenerate four-wave mixing reflectivity of photorefractive GaAs at 1.06 μm.
Abstract: We have used a 20-kHz ac square-wave electric field to enhance the beam-coupling gain and the degenerate four-wave mixing reflectivity of photorefractive GaAs at 1.06 μm. The largest measured four-wave mixing reflectivity in the steady state was 15% at a grating period of 9 μm and an applied voltage of 3.2 kV across 0.4 cm. Theoretical results predict substantially higher reflectivity values for a field of 8 kV/cm; the origin of this discrepancy is thought to be space-charge effects that prevent us from obtaining the full field inside the crystal. We have also measured a transient reflectivity of 510% during the switch on of the backward pump beam. Finally, we have determined the accuracy of wave-front reversal through measurements of piston-error correction and conjugation fidelity.
40 citations