Showing papers on "Four-wave mixing published in 1982"
TL;DR: Continuous-wave phase conjugation of an image-bearing beam is demonstrated using a single-domain crystal of BaTiO(3) and nothing else and has a phase-conjugate reflectivity of 30%.
Abstract: Continuous-wave phase conjugation of an image-bearing beam is demonstrated using a single-domain crystal of BaTiO(3) and nothing else. The device operates by four-wave mixing using the photorefractive effect but without any external pumping beams or external mirrors. The customary pumping beams are derived from the incident beam and are internally reflected inside the crystal adjacent to an edge. The device is self-starting and has a phase-conjugate reflectivity of 30%. Imaging applications are discussed.
698 citations
TL;DR: Transfer of modulation from a phase-modulated laser beam to an unmodulated, oppositely running beam occurs in a sufficiently nonlinear resonant gaseous medium and heterodyne detection of the transferred modulation reveals multiplet patterns that are distinct for the two mechanisms.
Abstract: Transfer of modulation from a phase-modulated laser beam to an unmodulated, oppositely running beam occurs in a sufficiently nonlinear resonant gaseous medium. Two mechanisms account for this transfer: modulated hole burning and reflection from an induced population grating. Heterodyne detection of the transferred modulation reveals multiplet patterns that are distinct for the two mechanisms. In particular, a central dispersion feature in the dispersive phase pattern is a diagnostic indication of the reflection process.
276 citations
TL;DR: It is found that a phase-conjugate mirror with depleted pumps may exhibit bistability, and an exact solution of a nonlinear model of holographic four-wave mixing is derived.
Abstract: 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.
104 citations
TL;DR: In this paper, a review of various nonlinear optical mechanisms that may be used for DFWM, as well as the various DFWM and related "transient grating" experiments that have been performed for application to phase conjugation and to carrier dynamics studies are presented.
Abstract: Semiconductors appear to have excellent potential as materials for phase conjugation via degenerate four-wave mixing (DFWM) because of the large variety of nonlinear optical mechanisms that may be invoked in them. When the optical wavelength is near or above the band gap, mobile particles such as free electrons and holes or free excitons may be created; in such cases, DFWM itself provides a powerful contact-free and nondestructive technique for the study of carrier transport and decay parameters, such as ambipolar diffusion coefficients and recombination times. In this article, we briefly review the various nonlinear mechanisms that may be used for DFWM, as well as the various DFWM and related "transient grating" experiments that have been performed for application to phase conjugation and to carrier dynamics studies.
76 citations
TL;DR: A proposal and an analysis are presented for imaging through a distorting medium using field multiplication by four-wave mixing to study the properties of Na6(CO3)2, Na2SO4, and Na2CO3 in soda ash.
Abstract: A proposal and an analysis are presented for imaging through a distorting medium using field multiplication by four-wave mixing.
53 citations
TL;DR: In this article, it was shown that if sum or difference frequency generation or four-wave mixing occurs, the response to left and right circularly polarized light should be different in an optically active medium.
Abstract: It is shown that, in an optically active medium, if sum or difference frequency generation or four‐wave mixing occurs, the response to left and right circularly polarized light should be different. Similar effects are studied where, in analogy to the Faraday effect, the optical activity is induced by an external static magnetic field.
52 citations
TL;DR: In this paper, the effects of finite pump beam correlation length in four-wave mixing processes were investigated. But the model was not applied to the case of a KrF laser-pumped methane Raman amplifier.
Abstract: Intensity averaging of pump beams in a Raman amplifier can be treated using a four-wave mixing model. The model shows explicitly the consequences of finite pump beam correlation length in four-wave mixing processes. Phase conjugate effects in a Raman amplitier are observed and described. Measurements of four-wave mixing effects in a KrF laser-pumped methane Raman amplifier agree with the model.
51 citations
TL;DR: In this article, the general formalism of transient four-wave mixing is developed using the diagrammatic technique of Yee and Gustafson, and applied systematically to two-, three-, and four-level systems.
Abstract: The general formalism of transient four-wave mixing is developed using the diagrammatic technique of Yee and Gustafson, and applied systematically to two-, three-, and four-level systems. The results predict all possible photon-echo phenomena including free-induction decay in the low-intensity limit. Connections to transient saturation spectroscopy and other coherent transient effects can also be made. The treatment can be readily extended to the more general problem of coherent transient optical effects with $n$ waves.
45 citations
TL;DR: In this paper, the phase-sensitive detection of the beat signal is studied by means of a perturbation calculation of the nonlinear response of the medium, carried out to the third order in the incident fields.
Abstract: In this article, we analyse a new sensitive spectroscopic technique in which a sample cell is irradiated by a two-frequency pump beam (ω + Δ ± δ/2) and a counter-propagating probe beam (ω). The phase-conjugate fields re-emitted at frequencies ω ± δ, via four-wave mixing processes, are detected through their heterodyne beating with the probe field. The properties of the heterodyne beat signal are studied by means of a perturbation calculation of the nonlinear response of the medium, carried out to the third order in the incident fields. In resonant gas media, the emission lineshape exhibits a Doppler-free doublet structure [frequency splitting 3 δ/2 for single-photon resonances, and δ/2 for two-photon transitions]. By using a phase-sensitive detection of the beat signal, one can separately analyse real (dispersion) or imaginary parts (absorption) of the nonlinear susceptibility. For single-photon transitions, the signal phase shift is related to the atomic levels lifetime and allows one to study the relaxation dynamics in gas phase (like quenching collisions, velocity diffusion, etc...). This is particularly interesting for cross-over resonances, in which only the common level contributes. In three-level systems, one also predicts a selective resonant enhancement of the phase-conjugate emission through Raman-type two-photon processes. Most of these predictions have been experimentally verified.
39 citations
TL;DR: It is shown that complex-conjugate wave fronts can be generated and that distorted optical wave frontsCan be effectively corrected by degenerate four-wave mixing experiments in KNbO(3):Fe(2+).
Abstract: The electric-field dependence of the wave-front reflectivity ρ in degenerate four-wave mixing experiments with reduced KNbO3 and Bi12GeO20 has been measured and compared with the theoretical expressions [N. Kukhtarev et al., Ferroelectrics 22, 949, 961 (1979)] describing the influence of the different photoinduced space-charge fields in photorefractive media. Peak reflectivities of ρ = 1.4% for Bi12GeO20 and ρ = 10% for KNbO3:Fe2+ have been reached for field strengths of 12 and 8 kV/cm, respectively. It is shown that complex-conjugate wave fronts can be generated and that distorted optical wave fronts can be effectively corrected by degenerate four-wave mixing experiments in KNbO3:Fe2+.
37 citations
TL;DR: In this article, the use of resonantly enhanced four-wave mixing to generate high reflectivity phase-conjugate waves is discussed and a physical understanding of the mechanisms underlying the nonlinear response for a simple two-level system is presented followed by a discussion of the complicating effects of pump absorption, pump depletion, unbalanced pumps, and thermal motion.
Abstract: The use of resonantly enhanced four-wave mixing to generate high reflectivity phase-conjugate waves is discussed. A physical understanding of the mechanisms underlying the nonlinear response for a simple two-level system is presented followed by a discussion of the complicating effects of pump absorption, pump depletion, unbalanced pumps, and thermal motion. Modifications of the theory to describe four-level behavior are presented and compared with experiments. The application of nearly degenerate four-wave mixing to narrow-band filtering complicated by the A. C. Stark effect is dis-cussed along with examples of experimental observations.
TL;DR: A self-consistent description is given for the propagation of a weak optical probe beam through a homogeneously broadened two-level medium in the presence of a strong, collinear, near-resonant pump beam.
Abstract: A self-consistent description is given for the propagation of a weak optical probe beam through a homogeneously broadened two-level medium in the presence of a strong, collinear, near-resonant pump beam. The propagation of the probe beam is given in terms of bichromatic natural modes, which contain frequency components symmetrically displaced from that of the pump beam. The two frequency components have a definite relative amplitude and phase, which are determined solely by the frequency detunings of the optical fields from the atomic resonance and by the intensity of the pump field. A simple method for calculating these natural modes is derived, and their importance in describing nearly degenerate four-wave mixing, optical bistability, and the stability of homogeneously broadened ring lasers is discussed.
TL;DR: In this paper, a real-time image division is obtained by using four-wave mixing of a reflection hologram type with photorefractive Bi 12 GeO 20 crystals, which reverses the phase of the incident wave.
TL;DR: The versatility of degenerate four-wave mixing has made possible its application to two major areas of spatial information processing: distortion correction and mathematical operations.
Abstract: The versatility of degenerate four-wave mixing (D4WM) has made possible its application to two major areas of spatial information processing: distortion correction and mathematical operations. The first area can be divided into predetection and postdetection processing. Distortions can be compensated for before the imaging. process by exploiting the phase-conjugating capability of D4WM. Phase-conjugate mirrors (PCM's) may also find use in optical processors designed to remove distortions after the imaging process is complete and the object is no longer available. Examples of linear operations that can be implemented using the nonlinear optics of D4WM are image convolution and correlation. An example of a nonlinear mathematical operation that can be implemented using D4WM is edge detection of two-dimensional images.
TL;DR: In this paper, the phase volume hologram responsible for the phase-conjugate wavefront generation is a reflection hologram and the theoretical and experimental results for wavefront reflectivity as a function of the intensity ratio of the writing beams are given.
TL;DR: The spectrum of degenerate four-wave mixing on a homogeneously broadened one-photon transition is shown to exhibit line splitting when the pump-intensity difference exceeds the saturation intensity.
Abstract: The spectrum of degenerate four-wave mixing on a homogeneously broadened one-photon transition is shown to exhibit line splitting when the pump-intensity difference exceeds the saturation intensity. The splitting arises from a saturation mechanism reinforced by the pump imbalance. Experimental evidence of this effect, using SF6 as the nonlinear medium, is presented.
TL;DR: Polarization properties of phase-conjugate (PC) mirrors obtained by degenerate four-wave mixing in resonant gas media are experimentally analyzed and theoretically interpreted and it is shown that these properties are rather insensitive to the relaxation processes in the gas phase.
Abstract: Polarization properties of phase-conjugate (PC) mirrors obtained by degenerate four-wave mixing in resonant gas media are experimentally analyzed on various neon transitions and theoretically interpreted. We show that, because of the Doppler broadening of the decay rate of the gratings, these properties are rather insensitive to the relaxation processes in the gas phase. We demonstrate simple ways of characterizing PC mirrors with either λ/2 birefringence (for cross-polarized pumps) or J-dependent linear dichroism (for parallel-pump polarization).
TL;DR: In this paper, non-degenerate four-wave mixing using two noncollinear laser beams with frequencies (wavevectors) ω p, ω t ( k p, k t ) respectively is studied in CuCl.
TL;DR: In this article, degenerate four-wave mixing and two-dimensional phase conjugation of surface plasmons at an interface between a mental and a non-linear dielectric medium is considered.
TL;DR: Self-trapping of a pulsed dye-laser beam in sodium vapor is demonstrated and it is shown that the four-wave mixing process leading to conical emission occurs within these self-trapped filaments.
Abstract: Experimental evidence is presented that shows that the conical emission often found surrounding a near-resonant laser beam after it passes through an atomic vapor is due to nondegenerate four-wave mixing enhanced by the ac Stark effect We demonstrate self-trapping of a pulsed dye-laser beam in sodium vapor for wavelengths 004 to 10 A shorter than that of the D2 resonance and show that the four-wave mixing process leading to conical emission occurs within these self-trapped filaments
TL;DR: The fidelity of the phase-conjugate signal produced by degenerate four-wave mixing was evaluated by conjugating and recombining the multiple-beam output from a phase grating.
Abstract: The fidelity of the phase-conjugate signal produced by degenerate four-wave mixing was evaluated by conjugating and recombining the multiple-beam output from a phase grating. A single output beam resulted. If one or more of the beams emerging from the grating were blocked, additional beams appeared whose relative amplitudes agreed with theory for a perfect phase conjugator.
TL;DR: In this paper, the formulation of phase conjugation via nondegenerate four-wave mixing in a homogeneously broadened resonant medium is generalized to include saturating pump waves, and an ultrahigh-Q optical filter is predicted, showing both gain and a bandwidth less than the homogeneous linewidth of the atom.
Abstract: The formulation of phase conjugation via nondegenerate four-wave mixing in a homogeneously broadened resonant medium is generalized to include saturating pump waves. An ultrahigh- Q optical filter is predicted, showing both gain and a bandwidth less than the homogeneous linewidth of the atom. The dependence of the filter function on the ac Stark effect and on the use of asymmetric pump wave intensities is discussed. In addition, several new phenomena are shown which manifest themselves as a dip in the degenerate reflectivity at line center.
TL;DR: In this article, the physics underlying the degenerate four-wave mixing (DFWM) technique is presented, and its application to the measurement of energy decay and dephasing rates is considered in the regime of small absorption and coupling coefficients.
Abstract: The physics underlying the technique of degenerate four-wave mixing (DFWM) is presented. Its application to the measurement of energy decay and dephasing rates is considered in the regime of small absorption and coupling coefficients.
TL;DR: In this article, a deegenerate four wave mixing is produced by the single pulse of a mode-locked laser (duration 25 ps) and the intensities are measured.
TL;DR: In this paper, the authors studied four-wave mixing when both the two-photon transition between the ground state and an excited state mod 0> and the one-photone transition between that excited state and a autoionising state mod 1> are nearly resonant.
Abstract: The authors study four-wave mixing when both the two-photon transition between the ground state and an excited state mod 0> and the one-photon transition between that excited state and an autoionising state mod 1> are nearly resonant. When mod 0> and mod 1> are strongly coupled, one of the eigenstates resulting from their mixing is almost stable against ionisation under certain conditions of frequency and intensity. The authors show that in this case an efficient frequency conversion should be obtained, since losses due to ionisation are expected to be strongly reduced.
TL;DR: Prior and Bloembergen as discussed by the authors showed that the collisionless contribution to the extra resonance is associated with a three-photon scattering process which produces an extra-resonant signal intensity which is fourth order in the laser intensity.
Abstract: It is predicted that, at sufficiently high laser intensity, the recently observed Raman-type extra-resonant enhancement of four-wave mixing [Y. Prior, A. R. Bogdan, M. Dagenais, and N. Bloembergen, Phys. Rev. Lett. 46, 111 (1981)] should not vanish in the absence of collisions. The collisionless contribution to the extra resonance is associated with a three-photon scattering process which produces an extra-resonant signal intensity which is fourth order in the laser intensity.
TL;DR: In this paper, the duration, shape, and background intensity level of pulses of a passively modelocked Nd-glass laser are determined by noncollinear phase-matched four-photon frequency mixing of time-separated fundamental and second-harmonic pulses in a KI crystal.
Abstract: The duration, shape, and background intensity level of pulses of a passively modelocked Nd-glass laser are determined by noncollinear phase-matched four-photon frequency mixing of time-separated fundamental and second-harmonic pulses in a KI crystal. The pulse shape is found to be slightly asymmetric with slower trailing than rising parts. The background intensity level before and behind the main pulse is about 5¢10−6 the peak pulse intensity.
TL;DR: Doppler-free saturation spectroscopy performed in an rf discharge in mercury vapor has made it possible to identify clearly all the central components of the 546.1-nm transition.
Abstract: Doppler-free saturation spectroscopy performed in an rf discharge in mercury vapor has made it possible to identify clearly all the central components of the 546.1-nm transition.Resonant degenerate four-wave mixing has also been observed in this system at this wavelength.