2006 Fiscal Year Final Research Report Summary
Theoretical study on optical process in nanomaterial by using nonlinear susceptibility without cancellation terms
| Project/Area Number |
16540287
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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 |
Condensed matter physics I
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| Research Institution | Osaka University |
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Principal Investigator |
AJIKI Hiroshi Osaka University, Engineering Science, Assistant Professor, 基礎工学研究科, 助手 (60283735)
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| Co-Investigator(Kenkyū-buntansha) |
CHO Kikuo Toyota Physical and Chemical Research Institute, Other Department, Fellow, フェロー (60013489)
ISHIHARA Hajime Osaka Prefecture University, Engineering, Professor, 工学研究科, 教授 (60273611)
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| Project Period (FY) |
2004 – 2006
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| Keywords | third-order optical nonlinearity / microcavity / cavity QED / biexciton / entangled photon pair / quantum well / quantum dot |
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| Research Abstract |
In the ordinal expression of optical nonlinear susceptibility, many terms are cancelled with each other. If we leave the cancellation terms, the nonlinear susceptibility diverges in a bulk limit. In order to avoid this unphysical result, we should treat the cancellation problem carefully. So far, the cancellation problem was exactly treated in a simple model by Ishihara and Cho. However, it is almost impossible to remove the cancellation terms in the first principle calculation by usin the ordinal expression of the nonlinear susceptibility.
In this project, we have succeeded to derive a general expression of nonlinear susceptibility without cancellation terms in advance. The general expression helps us to calculate size dependence of nonlinear susceptibility without attention to the cancellation terms.
We have also studied optical nonlinear response of excitons in microcavity. So far, the optical nonlinearities of cavity systems were studied in a semiclassical treatment. However, we have shown that cavity quantum electrodynamics (cavity QED)is indispensable in order to study the optical nonlinearity of the cavity systems. Then, we study various nonlinear processes in the cavity QED treatment.
1.We have derived optimal conditions for achieving large optical nonlinearity of a single quantum dot in microcavity.
2.We have studied entangled photon generation due to the hyper-parametric process from a quantum well and quantum dot in microcavity. The efficiency of the generation is dramatically enhanced due to the cavity effect. We have also found optimal conditions for the entangled photon generation. These optimal conditions are qualitatively understood from the characteristic feature of the cavity QED.
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