| Project/Area Number |
17560040
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Applied optics/Quantum optical engineering
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| Research Institution | Ritsumeikan University |
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Principal Investigator |
KASAHARA Kenichi Ritsumeikan University, Department of Science and Engineering, Professor (70367994)
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| Co-Investigator(Kenkyū-buntansha) |
ARAKI Tsutomu Ritsumeikan University, Department of Science and Engineering, Associate Professor (20312126)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,750,000 (Direct Cost: ¥3,600,000、Indirect Cost: ¥150,000)
Fiscal Year 2007: ¥650,000 (Direct Cost: ¥500,000、Indirect Cost: ¥150,000)
Fiscal Year 2006: ¥1,400,000 (Direct Cost: ¥1,400,000)
Fiscal Year 2005: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Quantum Cascade Laser / Nitride Semiconductor / Optical Device / Environment / Life Science / 窒化物半導体 / 生命科学 |
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| Research Abstract |
We have performed two studies toward the goal of this project 1) Research on the gain curve of the quantum cascade laser (QCL): Knowing the electron distributions in the upper and lower subbands of the QCL, and the resultant gain curve is critical to reduce the threshold current, and to achieve room-temperature continuous-wave operation. Investigation of the QCL's linewidth enhancement factor (α-factor) offers clues about them. It has been predicted that QCLs would have an α of zero as a result of intersubband symmetric gains. Using a new asymmetric self-mixing method, we have first identified that α-factors of InGaAs/InAlAs QCLs are smaller than those of conventional semiconductor laser-diodes with interband transition, but not zero. We have also demonstrated the detuning property of the α-factor, which showed that the gain was asymmetric around the gain peak. The nonparabolicity of the subbands was a possible cause of the α-factor's asymmetry, which produces inhomogeneous broadening
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and an asymmetric optical gain spectrum with a long wavelength tail. Taking the nonparabolicity into account, we determined the QCL gain spectrum. The dependence of the α-factor on detuning was in reasonable agreement with the calculation that accounts for the asymmetry in gain. 2) Development of the InN/InGaN epitaxial growth technique: Non-polar A-plane (11-20) high In content InGaN was grown on R-plane (10-12) sapphire with an InN template by radio-frequency (RF) plasma assisted molecular beam epitaxy. Nitridation of R-plane sapphire was carried out at 300℃ by RF-nitrogen plasma. A template of A-plane InN was grown at 400℃. The In-rich InGaN films were then grown at the same temperature on the InN template. We characterized the films using reflection high-energy electron diffraction, X-ray diffraction, scanning electron microscopy and photo-luminescence (PL). These results indicated clearly that non-polar In_<0.71>Ga_<0.29>N was successfully obtained with a PL emission at approximate 1.1 eV. Less
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