MRI: Acquisition of Instrumentation for Optical Propagation Loss Measurement in Novel Waveguide Materials

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Integrated optical waveguides for information processing and transmission are characterized by core and cladding structures of slightly different refractive index. The refractive index contrast guides light rays within the core via total internal reflection. There is considerable motivation to develop materials synthesis and processing techniques that free integrated optics from complex vapor deposition fabrication processes. There is likewise demand for new materials and architectures that offer increased bandwidth and greater compositional flexibility than conventional silica-glass based and crystalline waveguide materials. We present results demonstrating that polymeric, glass nanocomposite, and colloidal sol-gel materials are highly promising waveguide materials that combine compositional flexibility with fast and relatively inexpensive processing requirements. Initial waveguide propagation loss investigations reveal these materials exhibit losses of order 2 dB/cm. Ongoing studies reveal that thermal reflowing of sol-gel waveguides is likely to reduce this loss below 1 dB/cm. Continuing investigation of polymeric guides has demonstrated that fluorinated branched electro-optic dyes can be incorporated in low loss polymer hosts with thin-film losses of well below 1 dB/cm. Both studies provide compelling evidence that these are promising new materials for waveguide applications. In addition, we present important results demonstrating that waveguide design, fabrication, and characterization is an excellent training opportunity for advanced physics and chemistry undergraduates, and fills a critical need in preparing students for advanced study in materials science. Continued progress on both research and student training is contingent on the acquisition of precision positioning and imaging equipment for the accurate measurement of optical propagation loss. Materials research has transformed the technological landscape through innovations such as optical fibers and lasers. For example, highly efficient semiconductor lasers are well-matched to low-loss optical fiber, resulting in a wealth of telecommunications developments such as high speed Internet transmission. The devices which prepare light signals for eventual transmission over fiber optic lines are referred to as integrated optics. All integrated optics have in common material structures called waveguides that confine light signals to well-defined regions smaller than the thickness of a human hair. There is considerable motivation for materials synthesis and processing techniques that simplify the fabrication of waveguide structures. At the same time, there is an urgent need to make the study of waveguide materials more accessible to undergraduate science students, in order to provide properly trained students for both graduate research and industry. Several promising approaches that satisfy both the technological and training needs of the materials research community are based on polymeric and colloidal sol-gel materials. Waveguides can be fabricated from these materials using simple coating techniques, and both offer considerable compositional flexibility. The utility of any novel waveguide material depends on its ability to transmit light with minimal attenuation, thus making the assessment of optical losses due to absorption and scattering an essential component of any waveguide materials research effort. Our preliminary results strongly suggest that polymeric and colloidal sol-gel materials can yield optical losses suitable for applications. Continued progress on both research and student training is contingent on the development of precision positioning and imaging equipment for the accurate measurement of optical propagation loss.