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
Capital Cities and Tombs of the Ancient Koguryo Kingdom main Goguryeo capital moved to Pyongyang. Wandu contains many vestiges including a large palace and many tombs. The capital cities of the Goguryeo are an early example of mountain cities later imitated by neighbouring cultures. The system of capital cities represented by Gungnae City and Wandu Mountain City also influenced the construction of later capitals built by the Goguryeo regime. The capital cities of the Goguryeo represent a perfect blending of human creation and nature whether with the rocks or with forests and rivers. The site includes archaeological remains of 40 tombs which were built by Goguryeo, which was founded