2000 Fiscal Year Final Research Report Summary
Radiation of THz electromagnetic waves from semiconductor microcavity polaritons
| Project/Area Number |
11650046
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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 | Hiroshima University |
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Principal Investigator |
KADOYA Yutaka Faculty of Engineering, Hiroshima University, Associate Professor, 工学部, 助教授 (90263730)
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| Co-Investigator(Kenkyū-buntansha) |
YAMANISHI Masamichi Faculty of Engineering, Hiroshima University, Professor, 工学部, 教授 (30081441)
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| Project Period (FY) |
1999 – 2000
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| Keywords | Semiconductor microcavity / Cavity-polaritons / THz electromagnetic waves / Quantum confinc Stark effect |
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| Research Abstract |
In this project, we studied the radiation of THz electromagnetic waves from exciton-polariton in semiconductor microcavities. In particular, we focused on demonstrating the experimental evidences of THz-wave radiation from cavity polaritons. Another aim has been the investigation of coherent dynamics of cavity polaritons using the THz wave observation as a probe. The obtained results can be summarized as follows.
1. Through our systematic experimental study, it was condidentially concluded that the THz wave is radiated from the nutation of exciton population, associated with the normal mode oscillation of cavity-polaritons under resonant excitation.
2. We found that the frequency of the THz-wave is slightly higher than that expected from the energy difference between the two polariton modes. Such a deviation was shown to result from the difference between the energy differences observed in reflection spectra and the eigen (normal) modes of the polariton system, through the experiment and
… More
theoretical considerations.
3. Increases of damping rates of the THz-waves were observed for the case that a high internal electric field is applied to the quantum wells. We showed that the faster damping is relevant to the broadening of exciton lines. Also, the damping rates were found to become higher under intense excitations.
4. With the decrease of the cavity Q value, we also observed the faster damping of the oscillation in the THz-wave. In particular, only a single cycle, but rather strong THz-wave emission was observed. The results are the other manifestation that the oscillatory THz signals in high-Q cavities are due to the nutation of exsciton populations.
5. We proposed a new scheme for the enhancement of THz electromagnetic wave radiation from semiconductor surfaces based on the efficient use of excitation power in bulk semiconductor microcavities. We demonstrated more than one-order of magnitude enhancement of the THz-wave radiation in comparison with off-the shelf bulk InAs which has been believed to be the best material for the THz-wave radiation. Less
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