Conjugated Polymers as Materials for Solid State Lasers

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9730126 Heeger Semiconducting polymers offer important advantages as potential laser materials, e.g., High photoluminescence efficiency (PL), low self-absorption, emission wavelengths that span the visible spectrum, easily processed into optical quality thin films, and electrically pumped in a diode configuration. The high PL efficiency and large cross-section for stimulated emission persist to high concentrations. In contrast to traditional laser dyes, conjugated polymers function as high gain laser materials in the solid state, neat and undiluted. To obtain lower thresholds and to generate coherent laser light, it is necessary to incorporate the conjugated polymer into a resonant structure. The goal of this research is to achieve low threshold optically pumped polymer lasers through improvements in materials and materials processing and through the creation of novel resonant structures. With sufficiently low thresholds, lasing structures fabricated from semiconducting polymers can be developed as cw lasers. For example they could be pumped with conventional light sources, or with blue-emitting LEDs (e.g. using the InGaN technology), or with solar radiation (solar powered lasers!). To accomplish this goal, significant improvements in the polymer materials are required to enable the high-Q resonant structures that are needed. These improvements and the related achievement of high-Q resonant structures with conjugated polymers as the gain media are the goals of the proposed research. The actual work will include: measurements of gain and loss in photopumped semiconducting polymer films; materials development including fabrication of high quality, low-loss optical thin film waveguides and expansion into new conjugated systems (new PPV derivatives, polyfluorene derivatives and spiro-conjugated materials); development of cladding materials; and evaluation of these conjugated materials in microcavities, in distributed feedback structures and in `whispe ring gallery mode' structures (micro-disks and micro-rings). %%% This research will provide fundamental understanding and potentially new and improved devices in the area of laser materials and electrically active polymers. ***