Y. M. Cai

Dispersion measurements of electric-field-induced second-harmonic generation and third-harmonic generation in conjugated linear chains

Experimental measurements of the frequency dependence of the isotropically averaged, molecular dc-induced second-harmonic susceptibility 〈γ(−2ω; ω, ω, 0)〉 and third-harmonic susceptibility 〈γ(−3ω; ω, ω, ω)〉 of conjugated linear-chain structures are in excellent agreement with the results of many-electron, multiple-excited-configuration-interaction calculations. For hexatriene, the N = 6 carbon site linear polyene chain, we demonstrate the first successful comparison, to our knowledge, between experiment and theory for the magnitude, sign, and dispersion of 〈γ(−2ω; ω, ω, 0)〉 and 〈γ(−3ω; ω, ω, ω)〉. These results provide experimental verification of the importance of electron-correlation effects in the third-order nonlinear-optical properties of conjugated structures. Measurements of 〈γ(−2ω; ω, ω, 0)〉 and 〈γ(−3ω; ω, ω, ω)〉 for β-carotene, the intermediate length, N = 22, conjugated chain, are also reported, and the frequency dependence is well described by a three-level model that is developed based on the results of the electron-correlation description of γijkl(−ω4; ω1, ω2, ω3) for shorter chains. Finally, through the detailed comparisons of 〈γ(−2ω; ω, ω, 0)〉 with 〈γ(−3ω; ω, ω, ω)〉 and of experiment with theory, as well as through examination of previously reported values of the macroscopic third-order susceptibility χ(3)(−ω4; ω1, ω2, ω3) of glasses by other nonlinear-optical techniques, it is demonstrated that the common reference standard for χ(3)(−ω4; ω1, ω2, ω3) of glass is inaccurate, and an improved value is recommended.

Dispersion of second‐order optical properties of new high thermal stability guest chromophores

A new class of high thermal stability fused‐ring guest chromophores intended for incorporation into highly stable host polyimides has been successfully developed. Thermal stabilities far in excess of 300 °C have been achieved for both the pure guest and the parent guest‐host systems. dc‐induced second harmonic generation measurements of the microscopic second order β of the guest chromophores in solution have been performed using an optical parametric generation technique. In the near‐infrared region, values of the standard product μβ of order 103×10−48 esu have been observed. These values are in good agreement with quantum many‐electron calculations.

Measurement of The Third Order Optical Susceptibility of Quasi-Two Dimensional Conjugated Discs: Silicon Naphthalocyanine

Abstract The isotropically averaged nonresonant microscopic third order susceptibility ⟨γ⟩ has been measured for a quasi-two dimensional metallophthalocyanine at several near infrared wavelengths. An infinite dilution extrapolation method employing the Maker fringe technique for third harmonic generation in the wedge configuration was developed for measurement of ⟨γ⟩ in liquid solutions and is presented in detail. At a fundamental wavelength of 1907 nm, ⟨γ⟩ of silicon naphthalocy-anine is measured to be −3140 ± 250 × 10−36 esu whereas ⟨γ⟩ is less than the experimental sensitivity of ±50 × 10−36 esu for a fundamental wavelength of 1543 nm. These results are discussed in terms of the dispersion of ⟨γ⟩ in the region between the 3ω resonances associated with the Q and B absorption bands.

Resonant and non-resonant third-order optical properties of metallophthalocyanines☆

Abstract Non-resonant third-harmonic generation and resonant saturable absorption measurements of liquid solutions of silicon naphthalocyanine are discussed. The results provide further insight into the non-linear optical properties previously reported for random glassy polymers containing silicon naphthalocyanine.

Second-order Nonlinear Optical Properties Of Bond Alternating Dipolar Structures

Second-order nonlinear susceptibilities of two dipolar quinoid molecules, DCNQI and TPHQ2, are calculated using extensive single- and double-excitation-configuration interaction (SDCI). In sharp contrast to polyene studies, no overcorrelation of the ground-state energy level is observed for either of the two structures, suggesting the adequacy of SDCI calculations for both the ground and one-photon states. The calculated second-order susceptibility of DCNQI is found to be in excellent agreement with the results of dc field-induced second-harmonic-generation measurements in solution and in Langmuir-Blodget films. The principal off-resonance electro-optic coefficient

Fundamental Nonlinear Optics Issues In Organic And Polymer Systems

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Third-order optical properties of quasi-two-dimensional conjugated discs: silicon naphthalocyanine

(-\ensuremath{\omega};0,\ensuremath{\omega}) at 0.65 eV is calculated to be -3000\ifmmode\times\else\texttimes\fi{}

Second-order nonlinear optical properties of thiopheno-quinoid dipolar structures

{10}^{\mathrm{\ensuremath{-}}30}

Enhanced Third Order Nonlinear Optical Responses from Optically Pumped Electronic Excited States

esu for TPHQ2, a 20-fold increase compared to the calculated value of -140\ifmmode\times\else\texttimes\fi{}

Experimental measurements and electron correlation theory of third-order nonlinear optical processes in linear chains

{10}^{\mathrm{\ensuremath{-}}30}