Roadmap to Gigahertz Organic Transistors

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Single waveguide silicon-organic hybrid modulator

We present a novel silicon-organic hybrid modulator based on an integrated dual-mode interferometer. The modulator offers a compact, simplified design and enhanced robustness to on-chip fluctuations of temperature compared to conventional Mach-Zehnder based systems. A prototype modulator showing a voltage dependent transmission spectrum is obtained by cladding a dual-mode waveguide in a 250 nm silicon-on-insulator technology with a customized organic electro-optic layer. Estimated phase shifts and corresponding figures of merit are discussed in this contribution. The used organic layer is based on the guest-host approach with customized donor-acceptor chromophore embedded and poled in a poly(methylmethacrylate) matrix. The presented prototype is to the best of the authors'' knowledge the first integrated single waveguide silicon-organic hybrid modulator

Push-pull thiophene chromophores for electro-optic applications: from 1D linear to beta-branched structures

We report the synthesis and characterization of a novel series of push-pull chromophores bearing 1D linear and beta-branched thiophenes as pi-conjugated spacers between a 2, 2, 4, 7-tetramethyl-1, 2, 3, 4-tetrahydroquinoline electron donor unit and dicyano- and tricyanovinylene electron acceptor groups. The effect of the introduction of beta-thiophenes on the linear and nonlinear (NLO) optical properties as well as electrochemical and thermal data is studied in detail by performing a comparative study between the branched and 1D linear systems. In addition, a parallel DFT computational study is used to evaluate structure-property relationships. The non-linear optical behavior of the molecules both in solution and in solid state as electro-optic (EO) films using a guest-host approach shows very promising performance for electro-optic applications with high molecular first hyperpolarizabilities (mu beta) of 4840 x 10(-48) esu and electro-optic coefficients r(33) reaching 650 pm V-1. One highlight is that the electro-optic films of the beta-branched chromophores are superior in terms of thermal stability in device operation as measured by a transmissive modified reflective Teng-Man method. This work provides guidelines for the design of improved electro-optic materials including beta-branched chromophores which could be useful for practical EO applications, where both enhanced beta and r(33) values together with chemical and thermal stability are necessary