| Co-Investigator(Kenkyū-buntansha) |
BABA Motoyoshi Institute for Solid State Physics, THE UNIVERSITY OF TOKYO, Technical Staff, 物性研究所, 教務職員 (60159077)
YOSHITA Masahiro Institute for Solid State Physics, THE UNIVERSITY OF TOKYO, Research Associate, 物性研究所, 助手 (30292759)
AKIYAMA Hidefumi Institute for Solid State Physics, THE UNIVERSITY OF TOKYO, Associate Professor, 物性研究所, 助教授 (40251491)
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| Research Abstract |
We develop novel device structures with simultaneous optical and electronic confinement such as quantum wire lasers, and study their lasing, absorption, and gain characteristics on the basis of our microscopic optical transmission measurement systems.
We first developed computation codes with the finite element methods for design and optimization of quantum-confined structures for electrons and photons. We also developed measurement systems for optically pumped lasing at various temperatures, top-view photoluminescence spectra and images, and transmission light from waveguides.
As for the cleaved-edge overgrown T-shaped quantum wire laser structures, we investigated the problem of interface roughness on (110) overgrowth surfaces, which limit the final quality of the structures, and resolved the problem by introducing a new growth interruption annealing method. We finally realized atomically flat interface without monolayer steps over several tens of micro-meters in lateral extent.
A single quantum wire laser, which is a combination of a single-mode 1-D quantum wire and a single-mode 1-D optical waveguide was fabricated. We observed its lasing for the first time in August 2001. The laser structure includes 2-D quantum wells and 3-D double-hetero-structures in the 1-D optical waveguide and a 2-D quantum well in a 2-D slab optical waveguide. In other words, it contains structures of 1D-electron-1D-photon together with 2D-electron- 1D-photon, 3D-electron-1D-photon, and 2D-electron- 2D-phbton. Furthermore, these structures all make lasing, so that we can compare lasing characteristics of all the structure simultaneously. In addition, we resolved absorption spectra of 1-D excitons and 1-D continuum states, and observed the Sommerfeld factor inherent to 1-D systems for the first time.
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