Control of exciton characteristics towards realization of frequency tunable terahertz wave source(Fostering Joint International Research)

2019 Fiscal Year Final Research Report

• Project/Area Number: 16KK0129
• Research Category: Fund for the Promotion of Joint International Research (Fostering Joint International Research)
• Allocation Type: Multi-year Fund
• Research Field: Electronic materials/Electric materials
• Research Institution: Kobe University
• Principal Investigator: Kojima Osamu 神戸大学, 工学研究科, 准教授 (00415845)
• Project Period (FY): 2017 – 2019
• Keywords: テラヘルツ電磁波 / 半導体 / 量子井戸 / 励起子 / 非線形光学 / 差周波混合

Outline of Final Research Achievements

The purpose of this study was to clarify the role of excitons in the generation of terahertz electromagnetic waves by difference frequency mixing using excitons in semiconductors. The semiconductor samples were fabricated at the University of Glasgow, which is an international collaborator, and optical measurements, including observation of terahertz electromagnetic waves, were performed at Kobe University. From the experimental results obtained by the modulation spectroscopy, the second harmonic generation using the ultrashort pulse, and so on, the effects of resonant excitation of a single exciton level could be clarified. On the other hand, the effect of excitation of two exciton levels is still unknown. This point will be clarified in future research.

Free Research Field

半導体光物性

Academic Significance and Societal Importance of the Research Achievements

半導体中の励起子は高い振動子強度を有していることから、光デバイスへの応用が期待される一方、GaAsでは束縛エネルギーが小さく、室温で励起子が安定に存在できないとされてきた。そのような状況で、室温で励起子を利用したデバイスへの提案ができた点は重要な意義があると考えている。さらに、半導体レーザーとの組み合わせで小型のテラヘルツ電磁波分光システムを実現できると期待でき、有毒または有害な分子を高速に検出できる小型システムは今後、社会的に必要とされると考えている。