Yasuhiko Arakawa Yasuhiko Arakawa Yasuhiko Arakawa (Japanese , "Arakawa Yasuhiko"; born 6 November 1952) is a Japanese physicist. His research focuses on semiconductor physics, including growth of nanostructures and their optoelectronic applications. Among his main achievements are the proposal of the concept of quantum dots and their application to quantum dot lasers, the observation of exciton-polariton Rabi-splitting in a semiconductor microcavity, or, recently, the first 3D photonic crystal nanocavity lasers with quantum dot gain. Yasuhiko Arakawa received a B.S. degree in 1975 and a Ph.D. degree in 1980, respectively, from the University of Tokyo, both in Electronics Engineering. In 1981 he became
Arakawa River (Fukushima) ineffective, and the river continued to periodically flood, culminating in a large-scale flood on August 5th, 1986. In 2004 the Arakawa River's flood control system was completely overhauled, and 13 new check dams were built along the main river and numerous other dams built on its tributaries. In 2008 the Agency for Cultural Affairs designated the Arakawa First Check Dam as a Registered Tangible Cultural Property. In 2007 the Arakawa River tied with six other rivers for having the best quality river water in country based on biochemical oxygen demand tests conducted by the Ministry of Land, Infrastructure, Transport and