This proposal was received in response to Nanoscale Science and Engineering initiative, NSF 01-157, category NER. This program will explore the feasibility of using field effect induced charge injection into semiconducting, single wall carbon nanotubes to modulate the intensity of the optical absorption in thin, optically uniform films of nanotubes. The approach combines and extends recent results showing that 1) nanotube absorption bands can be modulated by chemically and electrochemically induced shifts of the nanotube Fermi levels and 2) recent successes in nanotube based field effect transistors which rely on field gating to similarly shift the nanotube Fermi level. For bulk nanotube samples possessing typical diameters ranging from ~1.1 - 1.6 nm the absorption band of interest (the V1 to C1 transition for the semiconducting nanotubes) straddles the 1.55 mm wavelength having technological relevance in fiber optic communications. Use of the field effect for modulation will result in an all electrically addressable device, with high anticipated switching speeds. The research will involve development of electrically coupled nanotube films having good optical clarity, the integration of these films into transparent electrode, field-gated devices, and the exploration of chemical doping and nanotube-nanotube screening effects on the function of the devices. The proposal identifies a fundamentally new mechanism for effecting optical modulation and, if successful, should encourage further work both in optimizing the nanotube based implementation as well as the development of alternative materials and devices. In keeping with the University of Florida and the NSF mission of training future generations of scientists the program will fund the research of both graduate and undergraduate students. Historically under-represented groups in science will be particularly encouraged to participate.
