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: It is shown that the motion-induced degradation of the OPC turbidity-suppression effect through a dynamic scattering medium shares the same decorrelation time constant as that determined from speckle intensity autocorrelation - a popular conventional measure of scatterer movement.
Abstract: Light scattering in biological tissue significantly limits the accessible depth for localized optical interrogation and deep-tissue optical imaging. This challenge can be overcome by exploiting the time-reversal property of optical phase conjugation (OPC) to reverse multiple scattering events or suppress turbidity. However, in living tissue, scatterers are highly movable and the movement can disrupt time-reversal symmetry when there is a latency in the OPC playback. In this paper, we show that the motion-induced degradation of the OPC turbidity-suppression effect through a dynamic scattering medium shares the same decorrelation time constant as that determined from speckle intensity autocorrelation – a popular conventional measure of scatterer movement. We investigated this decorrelation characteristic time through a 1.5-mm-thick dorsal skin flap of a living mouse and found that it ranges from 50 ms to 2.5 s depending on the level of immobilization. This study provides information on relevant time scales for applying OPC to living tissues.
85 citations
TL;DR: In this article, photorefractive self-pumped phase-conjugation is examined at near-infrared wavelengths using doped BaTiO 3, and reflectivities are reported as high as 76% between 720 nm and 1004 nm due, as is believed, to a backward stimulated photore-fractive scattering mechanism.
85 citations
TL;DR: The temporal profile of photon-echo signals generated by combined gated cw and pulsed dye-laser excitation of the inhomogeneously broadened, 555.6-nm absorption line of (174)Yb vapor is studied to find that the echo profile is, after time reversal, essentially identical with that of the first excitation pulse.
Abstract: We have studied the temporal profile of photon-echo signals generated by combined gated cw and pulsed dye-laser excitation of the inhomogeneously broadened, 555.6-nm absorption line of 174Yb vapor. We find that the echo profile is, after time reversal, essentially identical with that of the first excitation pulse. We give a new analysis of this effect. Since time-reversed pulse reproduction should also occur in inhomogeneously broadened solid samples, and since we observe time-reversed reproduced pulses up to 4% as intense as the input pulse, this effect may have important applications in optical signal-processing systems.
84 citations
TL;DR: In this paper, phase conjugation via stimulated Brillouin scattering in CH4 gas has been used to correct amplifier aberrations in a Nd: YAG oscillator/amplifier system.
Abstract: Phase conjugation via stimulated Brillouin scattering in CH4 gas has been used to correct amplifier aberrations in a Nd: YAG oscillator/amplifier system. The single amplifier stage has been used in two-pass and four-pass arrangements. Using the four-pass arrangement incorporating compensation for thermal birefringence, a single-frequency diffraction-limited output of 350 mJ, in a compressed 6 ns pulse is achieved at 15 Hz repetition rate.
84 citations
TL;DR: It is shown that, whereas true time reversal of an amplitude pulse is not possible with continuous-wave pumping, this can be achieved by short-pulse pumping of a long, narrow, nonlinear medium, although time-dependent phase variations are not time reversed.
Abstract: Four-wave mixing with optical pulses is considered analytically. It is shown that, whereas true time reversal of an amplitude pulse is not possible with continuous-wave pumping, this can be achieved by short-pulse pumping of a long, narrow, nonlinear medium, although time-dependent phase variations are not time reversed.
84 citations