quartz, or 0.56 pm/V. [4] The w (2) of other ISAM thin films can be rapidly determined by comparison to this reference. Since the thickness of the ISAM films is much less than the second-harmonic coherence length, the observed secondharmonic intensity increases quadratically with the thickness of a given material. In this limit, the w (2) value is determined by Equation 1, where A is the coefficient of the fit to the second-harmonic intensity as a function of fundamental intensity and l is the path length through the sample, i.e., the film thickness.Although the second-harmonic intensity of the polydye 2 film shown in Figure 7 is slightly less than that of the reference film, the Poly S-119 film is 30 % thicker than the polydye 2 film. Equation 1 therefore results in a w (2) value of 0.62 pm/V, a 10 % increase over the Poly S-119 ISAM films. The polydye 1 film is much thinner than the reference film and yet exhibits a second-harmonic intensity twice as large as the Poly S-119 film. The w (2) of the polydye 1 film is thus found to be 3.61 pm/V, an increase of more than a factor of six over that of the ISAM films of commercially available NLO polymers.Measurements of the dependence of the second-harmonic intensity on the polarization of the incident fundamental beam can provide valuable information concerning the orientation of the NLO chromophores, which will not, in general, all be aligned strictly perpendicular to the substrate normal. Comparison of the SHG intensity observed with s-polarized fundamental to that observed with p-polarized fundamental provides a determination of the relative magnitudes of the w (2) zxx and w (2) zzz tensor components. If an isotropic refractive index and a single dominant tensor element of the molecular hyperpolarizability are assumed, the average tilt angle of the chromophores with respect to the film normal is given by Equation 2.The tilt angle should be minimized as much as possible in order to maximize the w (2) zzz tensor component. The polydye 1 film exhibited a tilt angle of 26, compared to 35 for the reference 68-bilayer poly S-119 ISAM film and 39 for typical poled polymer systems. The newly synthesized polydye 1 therefore exhibits not only a stronger w (2) response but also a higher degree of ordering than commercially available polymers.We have thus synthesized several novel NLO polymer dyes and ionically self-assembled these polydyes into thin films via a process that allows the production of micrometer-thick films. The ISAM technique inherently results in dipole alignment at room temperature, without the additional high-temperature processing that poled polymers require. Furthermore, the non-centrosymmetric structure of ISAM thin films is the thermodynamically stable state of the system and therefore the w (2) response should not exhibit decay over time. These novel polymer films exhibit substantial w (2) values as well as uniform growth and exceptional film ordering.Today's multimedia technology is based on semiconductor technology and on magnetic or magneto-optic st...

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The photoinduced anisotropy in polymers and copolymers with a mesogenic and a nonmesogenic azobenzene moiety in the side chain were investigated. The results of the light-induced optical anisotropy study in thin films obtained by means of polarized UV−vis and IR absorption spectroscopy are presented. Starting from in-plane optically isotropic samples, irradiation with polarized laser at 514 nm induces significant and long-term stable optical anisotropy. The build-up of the optical anisotropy has been followed by transient absorption experiments with time resolution in the range of seconds. The coupling of photoinduced alignment between the two different azobenzenes could be proven by irradiation in the absorption band of the nonmesogenic chromophore. In- and out-of-plane refractive indices were determined using attenuated total reflection waveguide spectroscopy. High values of the in-plane light-induced birefringence of up to 0.23 depending on the relative content of the mesogenic and the nonmesogenic azobenzene moiety in polymer were found. The pronounced dependence of the birefringence on probe wavelength suggests a resonant enhancement of refractive index in the visible region. Refractive indices as a function of wavelength were evaluated from the measured polarized absorption spectra using the Kramers−Kronig relationship. Comparison with the results from waveguide spectroscopy showed that the anisotropy and dispersion of the refractive index below the absorption could almost entirely be explained by the reorientation of the two side-chain groups of the copolymer.