We propose and demonstrate an all-optical tunable phase-preserving scheme for amplitude regeneration of amplitude modulated signals and phase modulated signals based on coherent optical nonlinear wave mixing using HNLF. A regeneration factor of 7 for OOK and a regeneration factor of 2.9 for BPSK are achieved.

We discuss the minimum energy dissipation required to perform one logic operation by degenerate four-wave mixing of optical pulses in resonant, nonresonant, and photorefractive media.

We show that one can generate the time-reversed replica of an "input" monochromatic, image-bearing beam by coupling it into a waveguide where it interacts with counterpropagating multimode "pump" waves of the same frequency. The nonlinear electric polarization density that is third order in the propagating electric fields in the guide medium generates the replica by the process of "four-wave mixin...

We consider the backward optical wave stimulated by a multimode, monochromatic, incident optical wave in a waveguide filled with a transparent nonlinear medium, when the incident wave is negligibly perturbed by the nonlinear processes. We derive the conditions on guide length, area, mode number, and Stokes shift in order that a given high percentage of the power in the backscattered field be the “phase conjugate” of the incident field, i.e., be proportional to its complex conjugate in the entrance plane of the waveguide.

We have measured the nonlinear optical susceptibility coefficient governing self-induced changes in the state of elliptical polarization of a monochromatic beam in 10 common solvents. These are the first such measurements at 1060 nm. We show how our results may be used to estimate self-focusing in these solvents and to clarify other non-linear optical properties.

Get PDF Email Share Share with Facebook Tweet This Post on reddit Share with LinkedIn Add to CiteULike Add to Mendeley Add to BibSonomy Get Citation Copy Citation Text Robert Hellwarth and Paul Christensen, "Nonlinear Optical Microscope Using Second Harmonic Generation," Appl. Opt. 14, 247-248 (1975) Export Citation BibTex Endnote (RIS) HTML Plain Text Citation alert Save article

A method is proposed by which one may determine the separate contributions of (a) the anharmonic interionic forces, and (b) the nonlinear electric dipole moment (the nonlinear dependence on ionic displacements) to the integral over infrared frequencies of the imaginary part ${\ensuremath{\epsilon}}_{2}(\ensuremath{\omega})$ of a material's dielectric function (times the frequency $\ensuremath{\omega}$). The results can be used to determine parameters needed to calculate other features of multiphonon absorption. The method does not depend on the nature or magnitude of the anharmonic forces, but does require a model for the quadratic term in the dipole moment. The parameters in this model are then determined from measurements of ${\ensuremath{\epsilon}}_{2}(\ensuremath{\omega})$ at several temperatures. We use the method to show from existing data the multiphonon contribution to the integral of $\ensuremath{\omega}{\ensuremath{\epsilon}}_{2}(\ensuremath{\omega})$ for cubic LiF arises predominantly from anharmonic forces.

Using a single-mode ruby laser we have made the first measurements of intensity-induced changes of the optical polarization (ellipse rotation) in solids, viz., fused quartz and Schott BK-7 and SF-7 glasses for which we have obtained the nonlinear susceptibility values ${c}_{1221}(\ensuremath{-}\ensuremath{\omega}, \ensuremath{\omega}, \ensuremath{\omega}, \ensuremath{-}\ensuremath{\omega})=1.5, 2.3, \mathrm{and} 9.9\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}15}$ esu, respectively. These values are accurate to within 10% relative to the value for liquid C${\mathrm{S}}_{2}$, which we used for calibration and determined from other experiments to be 37.8\ifmmode\times\else\texttimes\fi{}${10}^{\ensuremath{-}14}$ esu to within 2%. We also show theoretically that a comparison of these values with electric-field-induced birefringence (Kerr) data can determine uniquely the fractional contribution to both of purely electronic nonlinearities. Existing Kerr data are only accurate enough at present for us to conclude that the electronic nonlinearities might dominate our effect.

We have determined the two independent “fast” non-linear refractive indices for liquid mixtures of CS2 and CCI4 to within 5% relatively and 8% absolutely over their range of more than a decade. These indices describe non-linear propagation of optical pulses of arbitrary polarisation, which are of a too short duration to be affected by electrostriction. We report measurements, having relative accuracy better than 1 %, of the static Kerr constants of these mixtures. We combine these results with recent data on Rayleigh wing depolarisation ratios for the same mixtures to deduce the desired non-linear indices with the aid of molecular theory. The non-linear refractive index for linearly polarised light is shown to be two-thirds (±5%) of the index difference measured by the Kerr effect, at least for molar concentrations of CS2 greater than 10%. Our measured relative values of the mixture Kerr constants are predicted to within experimental error if one simply replaces the Lorentz local field factors in the classical theory by their 0.6 powers.

IIwe obtain h' U Q Q ss'(ss+ts+Ns) e »- (es+ts+ss) ac 3h'Accordingly, (A4) becomes s e "'"=s g s e»"=&~/(yj) j' (A6')The sums involved here can be evaluated by usingPoisson's formula' U -', (V/X') kTg~/s(Z) W'4(A/7 ') kTgs(Z), (A7)where X=k/(2srsnkT)'/s and the function and the one resulting from (A5) by a differentiation with respect to (/4j), namely,The free energy of the system can be calculated by means of the formula From (A5) and (A6) it follows that, in the limit ts -+ 0, s 1}1 (sr e» ~-P e /»'~l (ts j s=-~- -, 'L(sr//4 j)'/sa 1 j, (A5') "See D. Menzel, Fmndamesstat Formsstas of Physics, (Dover

In an effort to verify the hypothesis that molecular reorientation (ac Kerr effect) is responsible for the self-focusing of light beams in certain liquids, we have measured and compared the thresholds and other characteristics of self-focusing for circularly and linearly polarized beams incident on these liquids. We show that for plane waves propagating in a homogeneous, isotropic, ensemble of molecules having anisotropic polarizability tensors, the nonlinear index should be four times as great for linearly as for circularly polarized waves. The hope that this difference in indexes would be reflected in a four-fold increase in the threshold power for self-trapping when circularly instead of linearly polarized light is incident was not realized. In practice, the increase was always found to be much less. However, in every case studied, the trapped light from a beam, circularly polarized to better than 1 part in 200, was markedly, if not completely, depolarized as soon as self-trapping could be detected. We show qualitatively that this polarization instability should exist for all but linearly polarized light and for a variety of nonlinear mechanisms. However, in the absence of even an approximate quantitative theory of the self-trapping of light that is not linearly polarized, the comparative measurements of thresholds cannot be said either to verify or disprove the hypothesis of molecular reorientation.