Resonant Third-Order Optical Nonlinearities of Poly（methyl methacrylate） Films Containing J-Like Aggregates of a Thiadicarbocyanine Dye

The third-order optical nonlinearities and responses of poly（methyl methacrylate） （PMMA） coating films containing J-like aggregates of a thiadicarbocyanine dye, 3,3＇-diethyl-2,2＇-thiadicarbocyanine iodide （DTDC1）, are measured by degenerate four-wave mixing （DFWM） technique under resonant conditions. The temporal profiles of the DFWM signal of PMMA coating films containing J-like aggregates of DTDC1 are found to consist of three components： i.e., the coherent instantaneous nonlinear response （electronic response） and the two slow responses uqth decay time constants of about 0.8ps and about 7.0ps. The electronic component of the effective third-order nonlinear susceptibility, χc^（3）, of one of the present films is as high as about 2.1×10^-8 esu, and the figure of merit of third-order nonlinearity F （F=χ^（3）/α） is evaluated to be about 1.9 ×10^-13 esu cm at 850nm.     

Optical nonlinearity measurement of 4-（N-methyl,N-hydroxyethl）amino,4＇-nitroazobenzene using a transmittance technique with a phase object（T-PO） with top-hat beams at 600-nm wavelength

The transmittance technique with a phase object（T-PO）,for measuring optical nonlinear coefficients is proposed with a top-hat beam.The sensitivity of the T-PO with a top-hat beam is a factor of 4 greater than that with a Gaussian beam.The validity of this method is verified by measuring the nonlinearity of a well-characterized liquid,CS 2 at 532-nm wavelength.The ease of use of this method has been proved by measuring a new compound 4-（N-methyl,N-hydroxyethyl）amino,4＇-nitroazobenzene（ANAB） at 600-nm wavelength,indicating that this method can be extended to the measurement of optical nonlinearities in a wide-band spectrum.     

Ultrafast Third-Order Nonlinear Optical Response of Organic-Inorganic Hybrid Materials （C19H25N2）7Hn [P2Mo18-n Vn O62]

We have measured the third-order optical nonlinearity of the organic-inorganic hybrid materials of supermolecules (C19H25N2)7Hn [P2Mo18-n Vn O62] (n = 1, 2, 4, 5) and their reactants (C19H25N2) Br and Hn 6[P2Mo18-n Vn O62] by using the ultrafast optical Kerr effect at 830 nm wavelength, with time resolution of 115fs. By comparing the γ values of the supermolecules and their reactants, it is concluded that the charge-transfer eahanced remarkably the third-order optical nonlinearity of the compounds. With the increment of the number of the vanadium atoms,the electron distribution changed strongly and the γ value decreased dramatically.