Showing papers on "Phase conjugation published in 1983"
TL;DR: In this article, the density of wavefront dislocations for optical fields as a function of radiation parameters is investigated both theoretically and experimentally, and it is shown that a field with dislocation cannot be conjugated by means of flexible adaptive mirrors.
Abstract: The density of wave-front dislocations for optical fields as a function of radiation parameters is investigated both theoretically and experimentally. A field with dislocations cannot be conjugated by means of flexible adaptive mirrors.
197 citations
TL;DR: In this paper, a plane-wave analysis of a self-pumped phase conjugator is presented, which uses four-wave mixing to produce the phase-conjugate replica of an incident optical wave.
Abstract: We present a plane-wave analysis of a recently demonstrated self-pumped phase conjugator. This device uses four-wave mixing to produce the phase-conjugate replica of an incident optical wave. All the waves are derived from the single incident wave: there are no externally supplied pumping beams. We consider the case of four-wave mixing in two interaction regions coupled by simple reflection. We calculate the phase-conjugate reflectivity as a function of coupling strength, taking into account imperfect coupling between the two interaction regions, and show that there is a threshold coupling strength below which the reflectivity is zero and above which the reflectivity is multiple valued. We also compute the coupling strength per unit length for a photorefractive crystal of barium titanate.
161 citations
TL;DR: In this paper, a passive phase conjugate mirror based on four-wave mixing in an optical ring cavity is described, which 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.
Abstract: 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.
107 citations
TL;DR: The temporal distortion and spectral broadening of a pulse generated by the combined effects of group-velocity dispersion and self-phase modulation is removed by reflection of a cw-pumped, broadband, unityreflecting Kerr-like optical phase conjugator followed by retraversal of the nonlinear medium.
Abstract: We show that the temporal distortion and spectral broadening of a pulse generated by the combined effects of group-velocity dispersion and self-phase modulation is removed by reflection of a cw-pumped, broadband, unity-reflecting Kerr-like optical phase conjugator followed by retraversal of the nonlinear medium We also examine numerically the effects of finite linear loss in the material, of nonunity conjugate reflectivity, and of finite conjugator thickness
106 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: This research presents a novel probabilistic approach to estimating the response of the immune system to laser-spot assisted, 3D image analysis of central nervous system injury.
Abstract: Reference EPFL-ARTICLE-158578doi:10.1364/AO.22.003665View record in Web of Science Record created on 2010-11-25, modified on 2017-07-31
76 citations
TL;DR: A self-pumped phase conjugator is demonstrated that operates over a wide field of view,phase conjugates separate images without cross talk, and when pumped by one incident beam will self-oscillate with mirrors placed in all four quadrants.
Abstract: A self-pumped phase conjugator is demonstrated that operates over a wide field of view, phase conjugates separate images without cross talk, and when pumped by one incident beam will self-oscillate with mirrors placed in all four quadrants. The phase conjugator uses a single crystal of BaTiO3.
70 citations
TL;DR: In this paper, the correction of wave distortions by the technique of optical phase conjugation is examined first on the basis of a newly derived integral equation for scattering of monochromatic scalar waves in the presence of a phase-conjugate mirror.
Abstract: The correction of wave distortions by the technique of optical phase conjugation is examined first on the basis of a newly derived integral equation for scattering of monochromatic scalar waves in the presence of a phase-conjugate mirror. The solution is developed in an iterative series, and the first- and second-order terms are analyzed and illustrated diagrammatically. A generalization of the integral equation is then presented, which takes into account the electromagnetic nature of light. It is also shown that, if the conjugate wave is generated without losses or gains and with a complete reversal of polarization, a total elimination of distortions may be achieved by this technique under circumstances that frequently occur in practice.
70 citations
TL;DR: Wave-front phase compensation and shaping, and the ability to ignore amplitude fluctuations and compensate phase in real time over multiple pi radians of dynamic range, were demonstrated in two discrete-channel laboratory test systems containing one and nineteen resolution elements.
Abstract: An “all-optical” approach for the realization of adaptive optical systems potentially containing in excess of a million spatial-resolution elements is reported. A phase-measurement and -compensation technique called an interference phase loop is employed in conjunction with a monolithic optically addressed spatial light modulator (SLM). Wave-front phase compensation and shaping, and the ability to ignore amplitude fluctuations and compensate phase in real time over multiple π radians of dynamic range, were demonstrated in two discrete-channel laboratory test systems containing one and nineteen resolution elements. All-optical phase compensation with a monolithic SLM was also successfully demonstrated.
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
01 Jan 1983
TL;DR: An experimental investigation of phase conjugation and pulse compression by stimulated Raman scattering in methane gas using a narrow-linewidth KrF-laser pump is presented.
Abstract: An experimental investigation of phase conjugation and pulse compression by stimulated Raman scattering in methane gas using a narrow-linewidth KrF-laser pump is presented. Good spatial reproduction of the pump beam is observed at reflectivities of up to 80%. With a pump-pulse duration of 25 nsec, backward Stokes pulses of 5-nsec duration with 40% of the 100-mJ pump energy were obtained.
TL;DR: In this article, phase conjugation in stimulated Brillouin scattering (SBS) from an optical waveguide is studied numerically, using a Cartesian two-dimensional propagation code (bounce) that includes pump depletion.
Abstract: Phase conjugation in stimulated Brillouin scattering (SBS) from an optical waveguide is studied numerically, using a Cartesian two-dimensional propagation code (bounce) that includes pump depletion. The simulations show that light scattered back through a phase aberrator produces a far-field profile closely matching that of the incident beam; however, the near-field intensity exhibits large and rapid spatial inhomogeneities across the entire aberrator, even for conjugation fidelities H as high as 98%. This effect can be only partially removed by spatial-filtering techniques. The dependence of H on SBS gain, scattering length L, and the average intensity Ī and angular divergence θD of the pump beam is first studied in the low-reflectivity regime (i.e., ignoring pump depletion). For amplitude gains ≳e10, H decreases monotonically with the factor Ī/θD that is due to a small-scale intensity pulling effect. This result appears to be independent of whether θD arises entirely from the aberrator or from a combination of the aberrator plus curvature introduced by a lens. In all cases, pump depletion is found to enhance the fidelity by inhibiting the small-scale pulling effect. Under appropriate conditions, this can actually reverse the intensity dependence of H seen in the absence of pump depletion.
TL;DR: Efficient, diffraction-limited phase conjugation of a XeCl laser beam (308 nm) using stimulated Brillouin scattering is reported using stimulated Brilliant scattering to conjugate heptane or ethanol into ethanol.
Abstract: We report efficient, diffraction-limited phase conjugation of a XeCl laser beam (308 nm) using stimulated Brillouin scattering. Reflectivities approaching 100% are obtained by focusing a XeCl laser (<0.15-cm(-1) linewidth) at 300 GW/cm(2) into heptane or ethanol.
TL;DR: In this article, it was shown that frequency detuning and phase mismatch effects can strongly affect the reflection coefficient of Brillouin enhanced four-wave mixing, and that extremely large reflectivities can be obtained if the intensities and frequency of the pump beams and the length of the interaction region all take on certain critical values.
TL;DR: In this article, thermally induced nonlinearities in the index of refraction are investigated for the case of degenerate four-wave mixing (DFWM), and an expression for the reflectivity is derived within the framework of a coupled thermodynamic-electromagnetic theory.
Abstract: Aspects of thermally induced nonlinearities in the index of refraction are investigated for the case of degenerate four-wave mixing (DFWM). An expression for the reflectivity is derived within the framework of a coupled thermodynamic–electromagnetic theory, and some implications for the conjugation efficiency are briefly discussed. We also report on experimental measurements of phase-conjugate reflectivities in excess of 200% at 532 nm and comment on the role of saturation effects and pump delays in obtaining the observed efficiencies. Finally, the results of near-field conjugation beam-quality studies are presented with a view toward examining some of the parameters crucial to conjugation fidelity in typical DFWM experimental setups.
TL;DR: In this article, it was shown that a simple lens is sufficient for transmitting the intensity of an image through a thin distorter and that a phase conjugator and a lens can transmit the amplitude of a single image through the same distorter.
Abstract: The problem of sending an optical image through a phase‐distorting medium is discussed. It is shown that a simple lens is sufficient for transmitting the intensity of an image through a thin distorter. A phase conjugator and a lens can transmit the amplitude of an image through a thin distorter. Neither can transmit an undistorted image through a thick distorter. These results are experimentally verified using a self‐pumped phase conjugator.
TL;DR: In this article, complete Raman spectra of transparent media are obtained with a single 10nsec, 10mJ, laser pulse by a new spectroscopic technique which exploits resonant behavior of nondegenerate four-wave mixing in the phase-conjugate geometry.
Abstract: Complete Raman spectra of transparent media are obtained with a single 10-nsec, 10-mJ, laser pulse by a new spectroscopic technique which exploits resonant behavior of nondegenerate four-wave mixing in the phase-conjugate geometry.
TL;DR: The saturation behavior of band-gap resonant optical nonlinearity is studied by degenerate four-wave mixing experiments at 10.6 microm in HgCdTe over a wide range of laser intensities to form a theory based on the saturation of the interband absorption at the pump frequency resulting from state blocking.
Abstract: The saturation behavior of band-gap resonant optical nonlinearity is studied by degenerate four-wave mixing experiments at 10.6 μm in HgCdTe over a wide range of laser intensities. The reflectivity clips at a constant level when the laser intensity is increased above 100 W/cm2, and the corresponding effective third-order nonlinear susceptibility drops as the inverse of the laser intensity. A theory based on the saturation of the interband absorption at the pump frequency resulting from state blocking is presented and agrees well with the experiment.
TL;DR: In this paper, the phase-conjugate beam fidelity in degenerate four-wave mixing with spatially varying pump beams is studied, including long-cell-length effects, diffraction, and nonlinear phase variation, focusing of the probe beam, and finally, losses.
Abstract: Phase-conjugate beam fidelity is studied in degenerate four-wave mixing with spatially varying pump beams. The theory includes long-cell-length (or high-gain) effects, diffraction, and nonlinear phase variation, focusing of the probe beam, and, finally, losses. Relatively simple algebraic expressions for the reflectivity are given that cover the cases of collinear or near-collinear beam geometries. An easily calculated parameter is defined that characterizes phase-conjugate fidelity and is applied to study focusing effects. It is shown that focusing effects may be useful in greatly reducing the principal distortion of the phase-conjugate beam over a considerable range of variation of beam parameters.
TL;DR: The time dependence of phase-conjugate wave generation in liquids has been studied using four-wave mixing of picosecond laser pulses and different polarization configurations.
Abstract: The time dependence of phase-conjugate wave generation in liquids has been studied using four-wave mixing of picosecond laser pulses and different polarization configurations. Response and decay times of some possible physical processes contributing to the phase-conjugate wave generation have been measured.
TL;DR: In this article, the authors measured phase-conjugate reflectivities of 11% at 193 nm by using stimulated Brillouin scattering of ArF laser radiation from 2,2,2-trifluoroethanol (CF3CH2OH).
Abstract: We have measured phase-conjugate reflectivities of 11% at 193 nm by using stimulated Brillouin scattering of ArF laser radiation from 2,2,2-trifluoroethanol (CF3CH2OH). This mirror has been shown to correct for the aberrations induced on the wave front by an ArF amplifier.
TL;DR: In this paper, phase conjugation by degenerate four-wave mixing in resonant gas media can be interpreted as a saturated absorption (SA) process produced by a spatially modulated pump beam.
TL;DR: In this paper, the effect of pump depletion on phase conjugation by degenerate frequency mixing (DFM) in saturable amplifiers, including the effects of pump depletions, a non-zero incident probe wave intensity and saturated gain of all waves in the nonlinear medium, is analyzed numerically.
TL;DR: In this article, the operator form of the wave equation is employed to indicate the symmetry properties of the diffracted field under coherent and partially coherent illumination, which are of interest in holography, phase conjugation, and for automatic focusing.
Abstract: The operator form of the solution for the wave equation is employed to indicate the symmetry properties of the diffracted field under coherent and partially coherent illumination. Such symmetries are of interest in holography, phase conjugation, and for automatic focusing.
TL;DR: In this article, the first reported fully quantum-mechanical theory of laser/optical bistability instabilities is presented, which shows how cavity side modes grow from spontaneous emission.
Abstract: We present the first reported fully quantum-mechanical theory of laser/optical-bistability instabilities that shows how cavity side modes grow from spontaneous emission. Because of three-wave mixing, a two-peaked spontaneous-emission spectrum is obtained in contrast to the three-peaked spectrum of resonance fluorescence. The theory is a multimode extension of Scully-Lamb theory that shows how population pulsations, combination tones, mode locking, and phase conjugation occur with quantum-mechanical fields.
TL;DR: In this paper, the saturation effects in phase conjugation in the case of gaussian beams were investigated, and the results can be drastically different from what is expected from a plane-wave analysis.
TL;DR: In this paper, a general formalism is developed to study intracavity phase conjugation through resonant degenerate four-wave mixing, and the effects of spatial hole burning, arising from interference of the counter-propagating pump waves, are fully incorporated.
Abstract: A general formalism is developed to study intracavity phase conjugation through resonant degenerate four-wave mixing. The effects of spatial hole burning, arising from interference of the counterpropagating pump waves, are fully incorporated. The analysis is applied to discuss intracavity phase conjugation in nonlinear media that can be modeled using either a two-level system or a Λ-type three-level system. In both cases, the phase-conjugate reflectivity exhibits bistability for an appropriate choice of the input parameters. For a two-level system, the tuning characteristics of the Fabry–Perot cavity significantly affect the phase-conjugate spectrum that displays hysteresis when the cavity is detuned from the applied laser frequency.