Role of Glass Composition in Waveguide Fabrication with Femtosecond Laser Pulses

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Tightly focused femtosecond (fs) laser pulses can be used to modify the refractive index of glass within the focal region of the laser beam. By scanning the glass with respect to the laser focus waveguide structures can be fabricated inside the glass. It has recently been observed that waveguide structures fabricated with fs laser pulses in a commercial phosphate glass (Schott IOG-1) behave qualitatively different from those in fused silica, the only glass that has been widely studied so far. In order to evaluate the general applicability of waveguide fabrication with fs lasers, this project involves an in-depth study of the effects of glass composition on waveguide fabrication with fs laser pulses. Experiments will be carried out to fabricate and characterize waveguides in a variety of glasses in order to identify compositions with favorable waveguide properties. The structural changes associated with waveguide formation will be investigated using optical microscopy as well as confocal fluorescence and Raman spectroscopy. The experimental results will be used to develop a detailed understanding of the relationship between the induced index changes, the structural modification and the thermo-mechanical properties of the glass. On this basis we plan to develop a general model for categorizing glasses in terms of their suitability for waveguide fabrication with fs laser pulses. The use of femtosecond (fs) laser pulses to fabricate optical waveguides holds tremendous potential as a fabrication technique for three-dimensional all-optical integrated components with applications in the photonics industry as well as in biological and chemical sensors and medical technology. The ability to use this technique with different types of glasses-specifically tailored for a specific photonics application- is critical to its successful exploitation. This project involves an experimental study of the effects of glass composition on waveguide fabrication with fs laser pulses. The experimental results will be used to develop a model that explains waveguide fabrication in glasses in terms of the physical, structural and thermo-mechanical properties of the glass. This research project is very multidisciplinary in nature, using theoretical concepts and experimental techniques ranging from materials science to laser physics to nonlinear optics. It offers a unique opportunity for education and training of graduate students by providing hands-on experience with state-of-the-art optical techniques, which are of great importance within the present and future photonics industry.