| Project/Area Number |
01550250
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
電子材料工学
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| Research Institution | Tokushima University |
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Principal Investigator |
SAKAI Shiro Tokushima University, Department of Electric and Electronic Engineering, Associate Professor, 工学部, 助教授 (20135411)
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| Co-Investigator(Kenkyū-buntansha) |
SHINTANI Yoshihiro Tokushima University, Technical College, Department of Electronics, Professor, 工業短期大学部, 教授 (40035613)
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| Project Period (FY) |
1989 – 1990
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| Project Status |
Completed (Fiscal Year 1990)
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| Budget Amount *help |
¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 1990: ¥600,000 (Direct Cost: ¥600,000)
Fiscal Year 1989: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Keywords | Optical switch / Lattice mismatch / Gallium arsenide on indium phosphide / Gallium arsenide on silicon / Hetero structure / Optical waveguide / ヘテロエピタキシ- / 熱歪 / 格子不整 / 光方向性結合器 / ガリウム砒素 / インジウムリン |
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| Research Abstract |
The optical switches operating at high frequency is required in optical computing and optical communication field. Although LiNbO_3 optical switches with on/off ratio exceeding 20 dB has already been realized, the integration of this switch with other optical devices like light sources and detectors is difficult. On the other hand, it is hard to control the accurate refractive index profile of the material system InGaAsP/InP which is important in the wavelength range of 1.3 to 1.6 mum, because the composition have to be selected to maintain the same lattice constant. AlGaAs which has the composition-independent-latitice constant is quite convenient to design the refractive index profile, however, it lacks the lattice matched substrate when it is combined with InGaAsP light sources. The purpose of this research project is to grow GaAlAs on lattice-mismatched substrate and to test its feasibility as a material for optical switches and waveguide devices. InPon which the lattice-matched In
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GaAsP/InP layers can be grown is first tried as a possible candidate to grow GaAs. Later, we used Si because the integration with other electronic devices is easy on this substrate.
As a first stage of the research project, a new optical directional coupler/switch in which the two channel waveguides are integrated in the vertical direction is proposed and designed. It is shown that the superlattice waveguide have advantage to fabricate this type of the structures. A new method to reduce both defect and thermal stress in GaAs grown on Si substrate is proposed and ixperimentally demonstrated. In this new methods, the GaAs/Si interface which acts as a dislocation source is partially eliminated. The double hetro structure optical wave guides are then fabricated and its propagation characteristics are shown to agree with the theoretically calculated ones. These research results clearly demonstrate that AlGaAs grown on lattice-mismatched substrate is quite useful in fabricating various optical devices. The research will continue to demonstrate some of the new devices using lattice-mismatched-heteroepitaxy. Less
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