Showing papers on "Phase conjugation published in 1985"
TL;DR: It is shown that the optical phase-conjugated reflectivity from silver and gold colloids is enhanced by several orders of magnitude and this enhancement is traced to the nonlinearities of the electrons in the metal particles and the value of their optical Kerr-effect coefficient is extracted.
Abstract: We show that the optical phase-conjugated reflectivity from silver and gold colloids is enhanced by several orders of magnitude. The reflectivity on resonance is comparable with that of CS(2) for metal-particle volume concentration of a few parts in 10(6). We trace this enhancement to the nonlinearities of the electrons in the metal particles and extract the value of their optical Kerr-effect coefficient.
527 citations
Book•
06 May 1985
TL;DR: In this paper, the authors introduce optical phase conjugation (OPC) and its application in four-wave mixing, and present specific features of OPC-SS and nonlinear mechanisms for FWM.
Abstract: 1. Introduction to Optical Phase Conjugation.- 2. Physics of Stimulated Scattering.- 3. Properties of Speckle-Inhomogeneous Fields.- 4. OPC by Backward Stimulated Scattering.- 5. Specific Features of OPC-SS.- 6. OPC in Four-Wave Mixing.- 7. Nonlinear Mechanisms for FWM.- 8. Other Methods of OPC.- References.
493 citations
TL;DR: In this paper, the authors demonstrate optical-beam phase conjugation by the process of two-beam coupling in photorefractive barium titanate and show that the incident, image-bearing beam causes exponential gain for counter-propagating waves, which are fed by noise and emerge with a power of the order of 10% of the incident beam.
Abstract: We demonstrate optical-beam phase conjugation by the process of two-beam coupling in photorefractive barium titanate The incident, image-bearing beam causes exponential gain for counterpropagating waves, which are fed by noise and emerge with a power of the order of 10% of the incident beam and phase conjugate to it This is expected from the calculated plane-wave gain plus the analogy to the theory of phase conjugation of complex wave fronts by stimulated Brillouin backscattering We conjugate beams at either 515 or 488 nm at between 10- and 50-mW power, and find, as expected, no frequency shift (<1 Hz) in the process
118 citations
TL;DR: In this article, the potential applications of these materials in wave mixing, phase conjugation, and optical bistability are discussed, and the extremely large optical nonlinearity and the slow response time of liquid crystals make them unique for studies of some highly nonlinear optical processes and their dynamic characteristics.
Abstract: Liquid crystals as nonlinear optical materials are reviewed. Potential applications of these materials in wave mixing, phase conjugation, and optical bistability are discussed. The extremely large optical nonlinearity and the slow response time of these materials make them unique for studies of some highly nonlinear optical processes and their dynamic characteristics.
96 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: The observation of optical phase conjugation utilizing the intrinsic Kerr-like nonlinear susceptibilities of two soluble polydiacetylenes was reported in this article, where the reflectivities of up to 40% were observed on a timescale of ≲100 ps and a value of χ(3)xyyx =7×10−12 esu evaluated.
Abstract: The observation of optical phase conjugation utilizing the intrinsic Kerr‐like nonlinear susceptibilities of two soluble polydiacetylenes is reported. Phase conjugate reflectivities of up to 40% were observed on a timescale of ≲100 ps and a value of χ(3)xyyx =7×10−12 esu evaluated.
82 citations
TL;DR: The first observation to the authors' knowledge of degenerate four-wave mixing in a sodium-seeded flame is reported and the theoretical dependence of the phase-conjugate output on the sodium concentration is verified experimentally, demonstrating the potential of this procedure as a diagnostic tool to measure species concentration in combusting or noncombusting media.
Abstract: The first observation to our knowledge of degenerate four-wave mixing in a sodium-seeded flame is reported. In addition, the theoretical dependence of the phase-conjugate output on the sodium concentration is verified experimentally, demonstrating the potential of this procedure for use as a diagnostic tool to measure species concentration in combusting or noncombusting media.
68 citations
TL;DR: In this paper, the phase conjugation is performed in a fluorescein film by a cw Ar ion laser of the wavelength 0.488 μm in a degenerate four-wave mixing (DFWM) configuration.
66 citations
TL;DR: In this paper, the conditions of high gain in wave-mixing experiments with photorefractive bit 2Si020 crystals were reviewed and applications to image amplification, laser beam steering, amplified phase conjugation, and self-induced optical cavities were presented.
Abstract: We review the conditions of high gain in wave-mixing experiments with photorefractive Bit 2Si020 crystals. These interactions are based on the recording of a moving interference pattern in the volume of the crystal ("drift" recording mode with an externally applied electric field). This technique has recently resulted in large values of the exponential gain coefficient r = 8 to 12 cm-1 for an optimized grating velocity and grating spacing. Applications to image amplification, laser beam steering, amplified phase conjugation, and self-induced optical cavities are presented.
61 citations
TL;DR: In this paper, a double-pass image transmission through a single multimode fiber is demonstrated, using a passive phase conjugate mirror, and an application to interferometry based on phase sensing is demonstrated.
Abstract: A double‐pass image transmission through a single multimode fiber is demonstrated, using a passive phase conjugate mirror. An application to interferometry based on phase sensing is demonstrated, by implementing the multimode fiber and the passive phase conjugate mirror as one arm of a Michelson interferometer. Due to the unique properties of the self‐pumped conjugator, nonuniform distortions caused by modal dispersion in the fiber and other aberrations are cancelled out, while uniform phase changes are detected.
60 citations
TL;DR: In this article, the most widely used methods of phase conjugation of light waves, stimulated Brillouin scattering and four-wave mixing, are described and the physical bases of both methods are shown.
Abstract: The time-reversal of light waves is discussed. Two of the most widely used methods of phase conjugation of light waves, stimulated Brillouin scattering and four-wave mixing, are described. The physical bases of both methods are shown. Two possible applications of optical phase conjugation, the production of highly directed laser beams and the self-targeting of radiation, are discussed.
TL;DR: In this paper, photorefractive passive phase conjugation of GaAlAs laser radiation at 815-865 nm and Ar+ laser radiation with BaTiO3 as the real-time holographic gain medium was reported.
Abstract: We report photorefractive passive phase conjugation of GaAlAs laser radiation at 815–865 nm and Ar+ laser radiation at 1090 nm. A ring passive phase conjugate mirror was used with BaTiO3 as the real‐time holographic gain medium. With GaAlAs lasers phase conjugate reflectivities of up to 16% uncorrected for Fresnel losses were recorded. Effects of the strong associated feedback to the laser and attempts at mode locking are described. At 1090 nm the reflectivity remains approximately the same, but with a significantly longer time constant.
TL;DR: In this article, a ring passive phase conjugator is described, where the ring may consist of a multimode fiber and a non-reciprocal phase shift in the fiber ring activates a grating movement and subsequent frequency detuning of the beams in a photorefractive four-wave mixer.
Abstract: A new optical rotation sensor is described. It is a ring passive phase conjugator in which the ring may consist of a multimode fiber. A nonreciprocal phase shift in the ‘‘passive’’ like fiber ring activates a grating movement and subsequent frequency detuning of the beams in a photorefractive four‐wave mixer. This device has the advantages of natural reciprocal behavior of phase conjugate beams (essential for rotation sensing) and has several adjustable controlling parameters. It reveals a new class of interferometry in which changes in the ring’s optical phases, the beam’s intensities and losses, and the mixing crystal’s efficiency and electric field modulate a frequency detuning of the oscillating beams.
TL;DR: In this article, it was shown that homogeneous and inhomogeneous components of a wave field have quite different symmetry properties under phase conjugation, and the results are illustrated by a discussion of the behavior of plane waves, both homogenous and evanescent ones.
Abstract: Several theorems are known concerning symmetry relations between monochromatic wave fields that propagate either into the same half-space (z > 0) or into complementary half-spaces (z > 0 and z < 0) and that are complex conjugates of each other in some cross-sectional plane z = constant. The theorems derived up to now apply only to wave fields that do not contain inhomogeneous (evanescent) components. In the present paper two of the main theorems are generalized to a wider class of fields. It is found that homogeneous and inhomogeneous components of a wave field have quite different symmetry properties under phase conjugation. The results are illustrated by a discussion of the behavior of plane waves, both homogeneous and evanescent ones, which undergo phase conjugation followed by transmission or by reflection.
TL;DR: In this article, the authors show that stimulated two-wave mixing is the origin of phase conjugate fields in self-pumped photorefractive mirrors, and predict that the bulk photovoltaic effect gives rise to an intensity-dependent frequency shift in the phase conjjugate field and is the physical origin for the occurrence of beam fanning.
Abstract: We show that stimulated two‐wave mixing is the origin of phase conjugate fields in self‐pumped photorefractive mirrors. We predict that the bulk photovoltaic effect gives rise to an intensity‐dependent frequency shift in the phase conjugate field and is the physical origin for the occurrence of beam fanning.
TL;DR: In this paper, it was shown that it is possible to increase the efficiency of stationary four-wave mixing in cubic photorefractive crystals of the sillenite family by using a holographic arrangement of the cubic crystal where the same volume phase hologram has opposite contrasts for orthogonally polarized light waves traversing the sample in opposite directions.
TL;DR: This optical oscillation locks the relative phase of the two phase-conjugate reflections such that they recombine at the beam splitter to form only a single beam as though they were truly time-reversed waves.
Abstract: A new type of interferometer has been constructed that uses a beam splitter and two self-pumped BaTiO3 crystals as phase-conjugate reflectors in place of the usual interferometer mirrors. Counterpropagating beams of light are spontaneously generated between the two crystals, coupling the pair of phase conjugators. This optical oscillation locks the relative phase of the two phase-conjugate reflections such that they recombine at the beam splitter to form only a single beam as though they were truly time-reversed waves.
TL;DR: In this article, the ring and semilinear passive phase conjugate mirrors use dynamic transmission holograms and may be pumped with light of short coherence length or with picosecond mode-locked laser light.
Abstract: Because the ring and semilinear passive phase conjugate mirrors use dynamic transmission holograms, they are insensitive to vibration and may be pumped with light of short coherence length or with picosecond mode‐locked laser light. Experimental demonstrations of these modes of operation are described.
01 Jan 1985
TL;DR: This chapter contains the basic ideas of optical phase conjugation in as popular a manner as possible and almost without the use of mathematics.
Abstract: This chapter contains the basic ideas of optical phase conjugation. We have tried to present them in as popular a manner as possible and almost without the use of mathematics. We also discuss applications of optical phase conjugation.
TL;DR: In this article, a new way of getting optical phase conjugation associated to frequency conversion (namely, frequency doubling, frequency multiplication or mixing) within a broad angular field of view was proposed.
Abstract: One proposes a new way of getting optical phase conjugation, associated to frequency conversion (namely, frequency doubling, frequency multiplication or mixing), within a broad angular field of view. This technique is based on nondegenerate, higher order multiwave mixing in a phase‐matched backward configuration. Applications to wave front reversal, spatial or temporal information processing with frequency up‐conversion are outlined.
Patent•
16 Dec 1985
TL;DR: The use of large sensor and phase shifter arrays in phase conjugation adaptive systems is currently limited by the computational power conventionally employed to solve small arrays as discussed by the authors, where the properties of sparse matrix mathematics may be used to efficiently calculate the extent of movement of a particular actuator to deform a mirror and thus compensate for phase distortions in an incoming wavefront.
Abstract: The use of large sensor and phase shifter arrays in phase conjugation adaptive systems is currently limited by the computational power conventionally employed to solve small arrays. Noting that in large arrays many of the derivatives of wavefront slopes are zero, then the properties of sparse matrix mathematics may be used to efficiently calculate the extent of movement of a particular actuator to deform a mirror and thus compensate for phase distortions in an incoming wavefront. Apparatus and methods are provided for handling such large arrays.
TL;DR: In this article, phase conjugation by stimulated Mandelstam Brillouin scattering in multimode fibres was investigated using a ruby pulsed pump with ∼ 500ns pulses.
Abstract: We report experimental studies of phase conjugation by stimulated Mandelstam Brillouin scattering in multimode fibres. A dramatic decrease in the threshold power as compared to that (104 to 105 W) typically observed in conventional media was achieved. A ruby pulsed pump with ∼ 500-ns pulses was used. For the 7-m-long fibre, the threshold power was ≈ 50 W, the degree of phase conjugation was almost one, the pump-to-Stokes conversion efficiency was about 80%. For the 130-m-long fibre, the threshold power decreased to ≈ 10 W and the pump-to-Stokes conversion efficiency reached 100%. Polarization scrambling was observed in the 130-m-long fibre, but the Stokes wave with polarization coinciding with that of the pump wave was a phase-conjugate replica of the pump, as before.
TL;DR: The first observation to the authors' knowledge of self-pumped phase conjugation in BaTiO(3) at 1.06 microm is reported, observed in two crystals purchased more than a year apart and poled at separate facilities.
Abstract: We report the first observation to our knowledge of self-pumped phase conjugation in BaTiO(3) at 1.06 microm. An essential feature is the lower threshold external ring configuration rather than total internal reflection geometry. Although the product of incident power (1 W/cm(2)) and formation time (600 sec) is much larger than the corresponding values at 0.80 microm (0.15 W/cm(2); 120 sec), the effect was observed in two crystals purchased more than a year apart and poled at separate facilities.
TL;DR: In this paper, a time domain single shot conjugation autocorrelator is described, where three beams derived from the same initial laser pulse interact in a nonlinear medium to produce a backward signal wave in a 90° phase conjugate geometry.
TL;DR: This paper treats the interaction of one strong classical field mode and one or two weak quantal modes with two-level systems in a purely operator formalism that complements the method presented and produces the same results.
Abstract: This paper treats the interaction of one strong classical field mode and one or two weak quantal modes with two-level systems. The analysis is carried out in a purely operator formalism that complements the method presented in the preceding paper and produces the same results. The present approach automatically collects all contributions to second order in the weak-field interactions, and can be easier to extend to more complicated cases. The analysis allows one to treat problems such as predicting the growth of sidemodes in laser- and optical-bistability instabilities, the resonance fluorescence spectrum, Rayleigh scattering, and quantum noise in small-signal phase conjugation.
TL;DR: In this paper, the authors observed wave front conjugation with amplified reflection return using the thermal nonlinearity of a thin film of nematic liquid crystal in conjunction with a low power laser (intensity on the order of 25 W/cm2).
Abstract: We have observed for the first time wave front conjugation with amplified reflection return using the thermal nonlinearity of a thin film of nematic liquid crystal in conjunction with a low power laser (intensity on the order of 25 W/cm2). Self‐oscillation is also observed.
TL;DR: In this article, it was shown that the first such bifurcation is in general sufficient to induce a quasi-periodic motion of the field phase, leading in practice to its complete indetermination.
Abstract: The intracavity intensity of an empty phase-conjugate resonator in which the phase-conjugate mirror is a Kerr medium with instantaneous response can exhibit a sequence of period-doubling bifurcations to chaos. We show that the first such bifurcation is in general already sufficient to induce a quasi-periodic motion of the field phase, leading in practice to its complete indetermination.
TL;DR: A phase-conjugate wave is generated by degenerate four-wave mixing in an amorphous chalcogenide As(2)S(3) thin film and the nonlinear absorption coefficient and refractive index are treated analytically and the results are compared with those of experiment.
Abstract: A phase-conjugate wave is generated by degenerate four-wave mixing in an amorphous chalcogenide As2S3 thin film. The time-dependent behaviors of the phase-conjugate wave, the nonlinear absorption coefficient, and the refractive index are treated analytically, and the results are compared with those of experiment. The analyses are based on the rate equations obtained from a simplified energy-band model of amorphous As2S3.