Multiwave Mixing Research Articles

Inhibiting the onset of the three-photon destructive interference in ultraslow propagation-enhanced four-wave mixing with dual induced transparency.

We propose a dual electromagnetically induced transparency (EIT) based multiwave mixing scheme that retains the significantly enhanced conversion efficiency enabled by ultraslow propagation of pump waves, yet is also capable of inhibiting and delaying the onset of the detrimental three-photon destructive interference that limits the further growth of the four-wave mixing (FWM) field. We show that the new scheme exhibits a wave-matching condition that is fundamentally different from the conventional FWM without EIT, and the efficient generation of the mixing wave is not critically dependent upon the FWM detuning to achieve constructive interference as required in the conventional FWM. These are significant steps forward in enabling applications of ultraslow wave nonlinear optics.

Three-photon destructive interference in ultraslow-propagation-enhanced four-wave mixing

We show that, although the efficiency of a multiwave mixing process can be significantly enhanced by an ultra-slowly-propagating pump wave, a three-photon destructive interference between the generated wave and the pump wave limits the final achievable conversion efficiency.

Optical Boolean logic based on degenerate multi-wave mixing in bR film

When two coherent beams interfere in bacteriorhodopsin (bR) film with a very small crossing angle, degenerate multi-wave mixing appears. In this paper, the properties of degenerate multi-wave mixing in bR film were studied. By use of degenerate multi-wave mixing in bR film, we realized optical Boolean logic operations.

Quadratic Interactions in Finite, One-Dimensional, Photonic Band Gap Structures with Deep Gratings: beyond the Undepleted Pump Regime

We theoretically study quadratic interactions in finite, one-dimensional, photonic band gap structures with deep gratings, under strong pumping and global phase matching conditions. For second harmonic generation, we findthat above a certain input intensity a dynamics reminiscent of a competitive, multi-wave mixing process takes hold: the pump field is mostly reflected, revealing a novel type of optical limiting behavior, while forward and backward generation is generally balanced. We also study the case of parametric down-conversion, where an intense second harmonic signal is injected in order to control a much weaker fundamental beam. Our results reveal the onset of a new process that has no counterpart in bulk materials: both transmission and reflection display an unexpected, unusual, resonance-like effect as functions of input second harmonic power.

Energy exchange properties during second-harmonic generation in finite one-dimensional photonic band-gap structures with deep gratings

We study second-harmonic generation in finite, one-dimensional, photonic band-gap structures with large index contrast in the regime of pump depletion and global phase-matching conditions. We report a number of surprising results: above a certain input intensity, field dynamics resemble a multiwave mixing process, where backward and forward components compete for the available energy; the pump field is mostly reflected, revealing a type of optical limiting behavior; and second-harmonic generation becomes balanced in both directions, showing unusual saturation effects with increasing pump intensity. This dynamics was unexpected, and it is bound to influence the way one goes about thinking and designing nonlinear frequency conversion devices in a practical way.

Electromagnetically induced transparency mediated by phonons in strongly coupled exciton-phonon systems

It is shown theoretically that electromagnetically induced transparency (EIT) due to strong exciton–phonon coupling can occur in strongly coupled exciton–phonon systems such as polymers and organic semiconductors and lead to ultra-slow light effects. The results indicate that the strong coupling of excitons and phonons is important, but the exciton– exciton interaction plays a small role in the generation of the EIT. Numerical results for polydiacetylene–toluene sulfonate are also presented. This EIT in a solid-state medium might be utilized for efficient multiwave mixing and quantum nondemolition measurements, as well as for novel acousto-optical devices.

Generation of a 160-GHz transform-limited pedestal-free pulse train through multiwave mixing compression of a dual-frequency beat signal

We report the experimental generation of a 160-GHz picosecond pulse train at 1550 nm, using multiple four-wave mixing temporal compression of an initial dual-frequency beat signal in the anomalous-dispersion regime of a nonzero dispersion-shifted fiber. Complete intensity and phase characterizations of the pulse train were carried out by means of a frequency-resolved optical gating technique, showing that 1.27-ps transform-limited pedestal-free Gaussian pulses were generated.

Coherent Oscillations in Multiwave Mixing Due to Higher-Order Coulomb Correlations

Coherent Oscillations in Multiwave Mixing Due to Higher-Order Coulomb Correlations

Coherent Oscillations in Multiwave Mixing Due to Higher-Order Coulomb Correlations

A three-beam configuration is used to investigate the spectrally resolved wave-mixing signal of a ZnSe single quantum well. The spectrum recorded in direction 2 k2–k1 shows coherent oscillations induced by a delayed third pulse with direction k3. Intensity and polarization-dependent measurements indicate that the signal is generated by a combination of four- and six-wave mixing. The origin of the oscillations can be explained qualitatively by a two-level model. The polarization-dependent experimental results require the treatment of many-body correlations and are well explained by microscopic calculations including four-particle correlations up to fifth order in the fields.

Effect of Optical Nonlinearity Dynamical Enhancement in Dye Doped Liquid Crystal Under A Electrical Field

We report observation of the dynamic enhancement of photorefractive effect in dye-doped nematic liquid crystal in the presence of an applied ac electric field. The multi-wave mixing efficiency in a planar cell with photoconductive orienting layers has been increased by two orders.

Coherent spectral oscillations in multiwave mixing

The nonlinear optical response of a ZnSe single quantum well is investigated by spectrally resolving a wave-mixing signal using a three-beam configuration. A delayed third pulse with direction ${\mathbf{k}}_{3}$ leads to coherent oscillations in the spectrum emitted in $2{\mathbf{k}}_{2}--{\mathbf{k}}_{1}.$ Polarization-dependent measurements highlight the importance of higher-order Coulomb correlations as the dominant coupling mechanism between the three pulses. The experimental results are well explained by microscopic calculations including four-particle correlations up to fifth order in the fields.

Intensity-dependent beam-fanning in high-gain photorefractive barium titanate crystal

A phenomenological multi-wave mixing model has been used along with a more general solution of Kukhtarev's model to explain intensity-dependent beam-fanning in photorefractive (PR) BaTiO3 crystal. The variation of trap density owing to the photoexcitation of charge carriers has been considered to explain the intensity-dependent effect. Theoretical results predicted by the model show a confirmation with experimental results obtained from PR crystal, and also show some of the controlling mechanisms that enable use of beam-fanning for some potential applications.

Theory of a collective atomic recoil laser

We perform a study of a collective atomic recoil laser ~CARL! that goes beyond the initial growth period. The study is based on a theory that treats both internal and external degrees of atomic freedom quantum mechanically but regards the laser light as a classical field obeying Maxwell’s equations. We introduce the concepts of momentum families and diffraction groups and organize the matter wave equations in terms of diffraction groups. The steady-state lasing conditions are discussed in connection with the probe gain in the recoil-induced resonances. The nontrivial steady states and the linear stability analysis of the steady states are both carried out by the method of two-dimensional continued fractions. Both stable and unstable nontrivial steady states are calculated and discussed in the context of regarding the CARL as multiwave mixing involving many modes of matter waves and two optical fields.

Algebraic method for solving a class of coupled-channel cavity QED models

A class of coupled-channel cavity QED models describing two-photon resonant Raman processes in multiple-\ensuremath{\Lambda} configuration are solved analytically by an algebraic method that introduces an angular momentum algebra for this multiwave mixing system.

Formation of Microporous Films via Pattern Photo-Polymerization Induced Phase Separation

We describe a method of fabricating microporous films through pattern photopolymerization induced phase separation in a mixture of solvent/monomer using multi-wave mixing, i.e., four-wave mixing through interference of two horizontal and two vertical waves. The simulation on the microporous forming process was undertaken in the framework of the time-dependent Ginzburg-Landau (TDGL) Model B equations coupled with the reaction kinetic equation of photopolymerization. In the total free energy description, Flory-Huggins free energy of mixing was combined with the elastic free energy of the network. The calculated results showed that the microporous size, shape, and spacing of the micropores depend on the angle of interference and the reaction rate controlled by the incident UV intensity.

Nonlinear formation of dynamic holograms and multiwave mixing in resonant media

The schemes of light beam transformations by volume dynamic holograms in resonant media revealing the fifth- or higher-order nonlinearities have been theoretically analyzed. N-wave mixing has been realized by changing of the propagation direction or frequency of the read-out wave in the solution of Rhodamine 6 G and polymethine 3274 U dyes. It has been demonstrated that the experimental results are in good agreement with the theoretical data obtained for a three-level medium model with due regard to absorption from the excited singlet level.

Nondegenerate Parametric Self-Oscillation via Multiwave Mixing in Coherent Atomic Media

We demonstrate an efficient nonlinear process in which Stokes and anti-Stokes components are generated spontaneously in a Raman-like, near resonant media driven by low power counter-propagating fields. Oscillation of this kind does not require optical cavity and can be viewed as a spontaneous formation of atomic coherence grating.

Diffraction-efficiency oscillations in amorphous As_2S_3 films

An experimental study of the holographic gratings recorded in nonannealed, thermally with time relaxed amorphous As2S3 films by 514.5-nm light in the presence of 632.8-nm readout light is carried out. The dependences of the maximal first-order diffraction efficiency on the holographic grating period was studied in a wide range of periods, from 0.40 to 70.0 µm. A peculiar oscillatory diffraction-efficiency temporal behavior occurring under certain conditions is reported. The obtained results are discussed in terms of photoinduced structural changes, relaxational structural changes, photoinduced anisotropy, and photoinduced recharging of the localized states in the bandgap. The diffraction-efficiency oscillations are explained by the model of annihilating defects and by multiwave mixing in a thin dynamic hologram.

Femtosecond, Frequency-Agile, Phase-Sensitive-Detected, Multi-Wave-Mixing Nonlinear Optical Spectroscopy Applied to π-Electron Photonic Materials

Degenerate four-wave mixing (DFWM) spectroscopy is modified to exploit femtosecond pulses, phase-sensitive-detection, frequency (wavelength) agility, two-color (nearly degenerate multiwave mixing) radiation, and improved signal-to-noise capabilities that can be realized through a combination of new solid state lasers, nonlinear optical components, and novel design concepts. The resulting time-resolved nonlinear optical techniques permit “instantaneous” optical nonlinearities, such as two-photon absorption cross sections, to be accurately measured over the spectral range from 450 to 2500 nm (and with significantly greater effort from 225 to 5000 nm). The power of the new techniques is illustrated by their application to the definition of Hg two-photon resonances of C60 and C70 as well as to the characterization of optical nonlinearities in two linear chromophores of putative utility for sensor protection and electrooptic modulation. Explicitly, these measurements provide accurate determination of both tran...

Phase conjugation of multicomponent Bose-Einstein condensates

We consider a trapped multicomponent atomic Bose-Einstein condensate, concentrating specifically on condensates in the hyperfine ground state $F=1,$ where spin exchange collisions result in a transfer of population between $m=0$ and $m=\ifmmode\pm\else\textpm\fi{}1$ internal states. Drawing an analogy with the optical situation, we show that this system can be regarded as a matter-wave analog of optical multiwave mixing. This opens up the way to realize matter-wave phase conjugation, whereby an incident atomic beam can be ``time reversed.'' In addition, matter-wave phase conjugation also offers novel diagnostic tools to study the coherence properties of condensates, as well as to measure the relative scattering lengths of hyperfine sublevels.