Preface This is an annual report on the research activities in the field of optical communications and high-speed electron devices for 2005 at the Graduate School of Science and Engineering, the Interdisciplinary Graduate School of Science and Engineering, and Quantum Nanoelectronics Research Center, Tokyo Institute of Technology. 　 These activities are initiated by Professor Yasuharu Suematsu (emeritus, the former president), and Professor Shigehisa Arai [Group A], mainly in the field of Low- Dimensional Quantum-Structure Lasers, Advanced Lasers for Photonic Integrations, and also in the fabrication of ultra-fine structures. 　 This report consists of a brief introduction of the research activities and a collection of the research papers published in 2005.