The ionic self-assembly monolayer process is a novel technique that has already been used to deposit ultrathin films on glass, polymer, and silicon substrates of different sizes and shapes. This technique is presented as a new tool with which to apply coatings on optical fibers. A nanometer-scale interferometric cavity was built up at the end of an optical fiber with discrete thickness increments of 4.75 nm for a total thickness of 1 mum . Theoretical and experimental aspects of the nanometer-scale Fabry-Perot cavity are described, and both theoretical and experimental results show good agreement.

Fabrication of organic thin films by spontaneous molecular assembly is a powerful tool for creating carefully controlled supramolecular structures for nonlinear optical (NLO) applications. Recently, Decher and co-workers extended the work of Iler et al. to a new method of depositing thin films by layer-by-layer adsorption of linear polyions. [1,2] This ionic self-assembled monolayer (ISAM) technique provides significant advantages over other thin-film fabrication methods, including long-term stability, ease of fabrication, and greater film thickness. We have fabricated NLO films hundreds of bilayers thick with consistent, reproducible film growth with each bilayer.The observation of NLO behavior in polymer/organic dye ISAM thin films using commercially available dye molecules, specifically Poly S-119 (from Sigma), has already been reported. [3,4] The polar ordering of molecules that occurs due to the inherent nature of the ISAM process suggests that a number of similar NLO thin films may be synthesized using both other standard chromophore dyes and molecules specifically designed to yield an enhanced macro-scale net dipole moment. Consequently, we have designed and synthesized several new NLO polymers, including poly(methacrylic acids) and polyesters (Fig. 1), and fabricated non-centrosymmetric thin films using the ISAM process. In this paper, we present results that demonstrate the second-order NLO behavior of these polydye materials.Multilayer thin films of designed and synthesized polydye 1, polydye 2, and polydye 4 were self-assembled on glass substrates with polydiallyldimethylammonium chloride (PDDA) as the passive polycation layer. Uniform polydye films with up to 88 bilayers have already been fabricated, with an average bilayer thickness of the order of 2 nm, based on ellipsometry data. We have previously described in detail the process of synthesis of more than 1000 ISAM layers with good surface morphology, [5±7] resulting in films micrometers thick.UV-vis spectroscopy was used to identify the absorption and transmission characteristics of the NLO thin films as well as to quantify the growth of the multilayer structures. For example, optical absorbance spectra measured during the growth of two PDDA/polydye films on modified glass substrates are shown in Figures 2 and 3. The absorbance peaks of polydye 2 and polydye 4 are located at 435 and 365 nm, respectively, and exhibit a linear increase with the addition of each bilayer. This demonstrates that each bilayer contributes an equal amount of material to the thinfilm growth. In addition, the maximum differences between data collected at different locations across each film are at most a few percent, indicating excellent uniformity of the films. The ISAM method therefore produces thin films that are homogeneous through the film thickness as well as across the width and length of the film.Thin-film emission characteristics have important implications for optical and optoelectronic devices. As examples, the fluorescence spectra of polydye 2 and polydye 4 ISA...

Fabrication of organic thin films by spontaneous molecular assembly is a powerful tool for creating carefully controlled supramolecular structures for nonlinear optical (NLO) applications. Recently, Decher and co-workers extended the work of Iler et al. to a new method of depositing thin films by layer-by-layer adsorption of linear polyions. [1,2] This ionic self-assembled monolayer (ISAM) technique provides significant advantages over other thin-film fabrication methods, including long-term stability, ease of fabrication, and greater film thickness. We have fabricated NLO films hundreds of bilayers thick with consistent, reproducible film growth with each bilayer. The observation of NLO behavior in polymer/organic dye ISAM thin films using commercially available dye molecules, specifically Poly S-119 (from Sigma), has already been reported. [3,4] The polar ordering of molecules that occurs due to the inherent nature of the ISAM process suggests that a number of similar NLO thin films may be synthesized using both other standard chromophore dyes and molecules specifically designed to yield an enhanced macro-scale net dipole moment. Consequently, we have designed and synthesized several new NLO polymers, including poly(methacrylic acids) and polyesters ( Fig. 1), and fabricated non-centrosymmetric thin films using the ISAM process. In this paper, we present results that demonstrate the second-order NLO behavior of these polydye materials. Multilayer thin films of designed and synthesized polydye 1, polydye 2, and polydye 4 were self-assembled on glass substrates with polydiallyldimethylammonium chloride (PDDA) as the passive polycation layer. Uniform polydye films with up to 88 bilayers have already been fabricated, with an average bilayer thickness of the order of 2 nm, based on ellipsometry data. We have previously described in detail the process of synthesis of more than 1000 ISAM layers with good surface morphology, [5±7] resulting in films micrometers thick. UV-vis spectroscopy was used to identify the absorption and transmission characteristics of the NLO thin films as well as to quantify the growth of the multilayer structures. For example, optical absorbance spectra measured during the growth of two PDDA/polydye films on modified glass substrates are shown in Figures 2 and 3. The absorbance peaks of polydye 2 and polydye 4 are located at 435 and 365 nm, respectively, and exhibit a linear increase with the addition of each bilayer. This demonstrates that each bilayer contributes an equal amount of material to the thinfilm growth. In addition, the maximum differences between data collected at different locations across each film are at most a few percent, indicating excellent uniformity of the films. The ISAM method therefore produces thin films that are homogeneous through the film thickness as well as across the width and length of the film.Thin-film emission characteristics have important implications for optical and optoelectronic devices. As examples, the fluorescence spectra of polydye 2 and polydye 4...

Multilayer thin films of metallic nanoclusters, polymers and other molecules have been formed using a novel electrostatic self-assembly method and analysed by multiple characterization techniques. Nanocluster size measurements, ellipsometry and UV-visible absorption spectroscopy have been used to confirm the linear build-up of the thin film thickness with the number of deposited nanocluster, polymer and other molecular layers. Auger electron spectroscopy allowed verification of the distribution of molecular species through thick films with multilayer segments containing different elements. Field emission scanning electron microscopy and atomic force microscopy permitted visualization of the morphologies of the outermost layers of the deposited films. Together, such characterization allows improved understanding and the basis for the design of multilayer thin film materials engineered to have specific molecular level structures and macroscopic functionalities.

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