Langmuir‐Blodgett (LB) film formation has been investigated for polymers in which non‐linear optical (NLO) moieties are attached to the side chain of a polymethacrylate (PMA) backbone. Polymer monolayers were successfully transferred onto hydrophilic glass substrates using a moving‐wall type LB trough. The LB films were characterized by pressure‐area isotherms, polarized ultraviolet visible spectra, ellipsometry, and second harmonic generation measurements. The characterization shows that NLO moieties in the side chain are inclined at a shallow angle to the plane of the substrate. The second‐order nonlinear optical coefficient and molecular hyperpolarizability were also calculated. © 1993 John Wiley & Sons, Inc.

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Temperature and frequency dependent measurements are utilized to study the relaxation behavior of a photocrosslinking nonlinear optical (NLO) material based on a polyvinylcinnamate (PVCN) polymer matrix. 3-cinnamoyloxy-4-[4-(N, N-diethylamino)-2-cinnamoyloxy phenyl azo] nitrobenzene (CNNB-R) is used as a functionalized NLO active dye. Measurements of dielectric properties of PVCN doped with different levels of CNNB-R have been performed. NLO dye molecules were bonded to the host polymer by ultraviolet irradiation. Measurements were carried out from 50 to 200 °C and a frequency range of 30 Hz to 1 MHz. The effects of dye content and UV irradiation on the dielectric response are discussed.

We report a novel method to obtain stable second order nonlinear optical (NLO) properties in polymeric thin films. Photocross-linking between the NLO active molecules and a photoreactive polymer is achieved by UV irradiation subsequent to poling. The thin film exhibits a nonlinear coefficient d33of 16.5 pm/V at a doping level of 20% by weight of NLO active molecules and possesses quite stable second order nonlinear optical properties.

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