Measurement of third-order nonlinear

Chen, Y. J. Carter, G. M. "Measurement of Third Order Nonlinear Susceptibilities by Surface Plasmons," Appl. Phys. 

The measurement of third-order nonlinear response, characterized by is simplified because no geometrical condition in the material is required. The intensity-dependent refractive index, a unique feature of the third-order nonlinear response, allows to characterize by smdying the change in the refractive index of the nonlinear material. This effect is exploited in numerous technical applications, and results in different experimental techniques that determine x - However, the absence of a geometrical condition in the material results in an extra complication when measurements are performed, since all materials (cell walls, glass, air,...) contribute to ... 

Thalhammer, M., Penzkofer. A. Measurement of third order nonlinear susceptibilitie.s by non-phase matched third harmonic generation, Appl. Phys. B 32, 137-143 (1983)... 

In this paper we report measurements of third-order nonlinearities for a group of bioengeneered polymers. These polymers and copolymers were synthesized from aromatic amine and phenolic compounds by a horseradish peroxidase catalized reaction in solution in an organic solvent containing buffer, with hydrogen peroxide as the oxidizing agent. 

Rao reported measurement of third-order optical non-linearity in the nanosecond and picosecond domains for phosphorus tetratolyl porphyrins bearing two hydroxyl groups in apical position [89]. Strong nonlinear absorption was found at both 532 nm and 600 nm. The high value of nonlinearity for nanosecond pulses is attributed to higher exited singlet and triplet states. Time resolved studies indicate an ultra-fast temporal evolution of the nonlinearity in this compound. 

The experimental technique used to measure the third order nonlinear susceptibilities of polydiacetylenes was developed recently at our laboratory. (15) This technique utilizes the intensity-dependent dispersion relation of confined modes of PDA films and determines by measuring the change of coupling angles with... 

This review covers the theoretical background and some of the practical aspects of nonlinear optics, including a description of the origins of third-order nonlinearities, systems of units that are encountered, experimental techniques that have been used or may be used to probe the third-order NLO properties of organometallic complexes, and computational methods that have or could be used to calculate third-order NLO properties. Subsequent sections collect comprehensive data of organometallic complexes in tables categorized by complex type and discussions of the results of third-order NLO measurements and calculations performed on organometallic... 

It is often difficult to get complete information on all the relevant parameters of third-order nonlinearity using one single technique. However, one can,use a combination of techniques to probe the various aspects of the x behavior. Here only two specific techniques to measure x are discussed. 

On the assumption of total symmetry of the tensor of third-order nonlinear polarizability c(— co coi, cog, cog), its non-zero and independent elements are the same as those of Table 12. Direct theoretical calculations of c = c(0 0,0,0) have been performed for the atoms of inert gases and some simple molecules. Values of the tensor elements = c(— cu cu, 0,0) have been determined for numerous molecules from static Kerr effect studies and values of c = c(— cd ot>,coi — col) from measurements of optical birefringence induced by laser li t. Measurements of second-harmonic generation by gases in the presence of a static electric field yield the tensor elements c " = c( — 2co co, to, 0), which can also be obtained from second-harmonic scattering in centro-symmetric liquids. The elements of the tensor c = c(— 3co co, co, co)... 

Several measuring techniques giving evidence of third-order nonlinear behavior are listed in Table 3.1 [26, 27]. 

In this paper we present some results of THG measurements in a solution of polydiacetylene at two laser wavelength 1.064 ym and 1.907 ym. The experimental arrangement, described elsewhere (6), allows not only an exact determination of third order nonlinear susceptibility, but also its phase. 

Long, H., Yang, G., Chen, A., Li, Y., and Lu, P. (2009) Femtosecond Z-scan measurement of third-order optical nonlinearities in anatase Xi02 thin films. Opt Commun., 282,... 

Ever since this technique was introduced by Sheik-Bahae a al, it has been extensively used for the study of third-order nonlinearity in solutions. a typical Z-scan measurement setup is shown in Figure 28. For a constant intensity, the sample could be moved along the z-axis to record the position-dependent variation in nonlinear phenomena. This technique is particularly useful in cases where nonlinear refraction is accompanied by TPA. Nonlinear refractive index (n2) is studied with a closed aperture or normalized aperture Z-scan technique. The TPA coefficient can be obtained through an open aperture Z-scan measurement. The effects arising out of both the real and imaginary parts of the nonlinear third-order susceptibility show up. Thus, for the measurement of ri2, two merit factors W and T are defined to account for the one-photon and two-photon absorptions, respectively ... 

There have been very few measurements made on the physical properties of Tg derivatives, their relative greater difficulty of preparation when compared with the Tg analogs has meant little interest in their properties. However, TglOSiMeslg has been found to show photoluminescence in the blue region of the spectrum, third-order nonlinear optical properties for TgMeg have been modeled, and electronic properties for and TgMeg have been calculated. 

Fig. 8. Examples of some of the donor-acceptor substituted TEEs prepared for the exploration of structure-property relationships in the second- and third-order nonlinear optical effects of fully two-dimensionally-conjugated chromophores. For all compounds, the second hyperpolarizability y [10 esu], measured by third harmonic generation experiments in CHCI3 solution at a laser frequency of either A = 1.9 or 2.1 (second value if shown) pm is given in parentheses. n.o. not obtained...

FIGURE 6.11 Third-order nonlinear snsceptibility as a function of a diameter of fused silica spheres. The dashed rectangle represents the independently measured )f of fused silica with the appropriate error bars (Sheik-Bahae et al. 1989). 

The dispersion of NLO properties is a major source of problems. Measurements are frequently available at one wavelength only, and the degree to which the results are influenced by material resonances close to the measurement wavelength is often difficult to quantify. It is possible to compensate for some of the dispersion effects in certain cases. However, unlike with second-order nonlinearity, the simple two-state model is generally considered insufficient for describing the dispersion of the third-order nonlinearity at least two excited states have to be considered. 

Both theoretical analysis and dipole moment measurements indicated that sulfonyl-substituted compounds may have ft coefficients similar in magnitude to their nitro analogues. Therefore, we have measured p for several sulfonyl- and nitro-substituted compounds using electric-field-induced second-harmonic generation method (EFISH) (11,25). In this experiment, one measures an effective third-order nonlinearity rEFISH for a solution containing the compound of interest, given by... 

In a recent communication we reported that the third order nonlinear optical susceptibility of Pt, Pb, and H2 tetrakis(cumylphenoxy)phthalocyanines was large and varied substantially with the metal substituent. (1) The structure of these compounds is shown in Fig. 1. The susceptibility was measured by degenerate four-wave mixing at 1.064 pm, a wavelength far from the main absorption bands of phthalocyanines near 650 nm. The nonlinear susceptibility of the Pt phthalocyanine was about a factor of 9 larger than that of the Pb phthalocyanine and a factor of 45 larger than the metal free compound. 

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