This project supports collaboration between Drs. Gary Tuttle and Kai-Ming Ho of the Department of Electrical Engineering at Iowa State University, in Ames, IA, and Dr. Ekmel Ozbay of the Department of Physics at Bilkent University, in Ankara, Turkey. The research will involve experimental and theoretical research in the area of photonic band gap materials. Using a new layer-by-layer photonic band gap structure, invented and demonstrated by the Iowa State group, as a basis, the scientists propose to work on four different issues of photonic crystals: THz crystals, defects, novel materials, and fabrication at infrared wave scales. The collaboration of the two research groups in the U.S. and Turkey should lead to the development of new experimental, and theoretical tools which will be used to understand the characteristics of these new materials. Such understanding will help to design and build photonic crystals which may be used for a variety of applications in millimeter-wave, infrared, and visible wavelengths such as millimeter-wave antennas, and thresholdless semiconductor lasers. Scope: This project will extend the collaboration between a senior scientist (Ho), a junior scientist (Tuttle), both from the U.S., with a junior Turkish scientist (Ozbay) after the latter has joined one of Turkey's most respected universities, Bilkent University. Dr. Ozbay has recently spent two and half years as a post-doctoral research fellow at Iowa State, where he, Tuttle, and Ho, have published four papers and submitted two more for publications in U.S. journals, in the area of condensed matter physics. The two sides intend to initiate the collaboration between Iowa State and Bilkent. At Iowa State, where Dr. Ho is the leader of the theoretical group, they have high performance computational facilities including massively parallel computing machines, appropriate computational programs, as well as excellent facilities for photonic band gap related fabrication. At Bilkent there is a newly completed microfabrication facility with a class 100 clean room, and various fabrication and testing equipment. The team at Bilkent will use that facility to fabricate photonic crystals at micron and submicron dimensions which require a true clean room environment, and will also use network analyzer to test the properties of crystals at microwave frequencies. The project meets the objectives of the Division of International Programs in linking US scientists with foreign scientists where the talents and capabilities are complementary, and by involving young scientists in international cooperation.