Plasmonic enhancement of photo-absorption in low-temperature-grown GaAs and its application to terahertz wave detection

2020 Fiscal Year Final Research Report

• Project/Area Number: 18K04980
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Review Section: Basic Section 30020:Optical engineering and photon science-related
• Research Institution: Hiroshima University
• Principal Investigator: Kadoya Yutaka 広島大学, 先進理工系科学研究科(先), 教授 (90263730)
• Project Period (FY): 2018-04-01 – 2021-03-31
• Keywords: テラヘルツ / 光伝導アンテナ / 低温成長GaAs / プラズモニクス / 非線形吸収

Outline of Final Research Achievements

We investigated the way of realizing high performance photoconductive antenna used in terahertz time-domain-spectroscopy based on the pulse laser working at 1.5 micrometer. In the photoconductive antennas made on low-temperature-grown GaAs which has very low noise characteristics, we enhance the nonlinear photo-absorption by utilizing surface plasmon resonance in nanometer-scale metal patterns and the Fabry-Perot resonance and eventually improve the efficiency of THz generation and sensitivity of THz detection. We clarified that by adopting a distributed Bragg reflector in the substrate, a large enhancement of light intensity can be realized in the device which can be fabricated based on the electron-beam lithography. In addition, we quantified the linear and nonlinear absorption coefficients in low-temperature-grown GaAs at 1.5 micrometer. Moreover, we clarified the device parameter dependence of the signal and noise in the photoconductive antenna made on low-temperature-grown GaAs.

Free Research Field

光デバイス工学

Academic Significance and Societal Importance of the Research Achievements

安定性，価格，小型化に優れたErドープファイバーレーザー駆動のテラヘルツ時間領域分光システムの高性能化が実現し，応用範囲が広がる．またファイバーを用いた可搬型のTHz波発生・検出素子が可能になり，極低温，強磁場等の特殊な環境下でのテラヘルツ時間領域分光が容易になる．また，プラズモニクス研究としては，半導体等の実用上重要な基板に設けたメタルナノパターンにおける近接場増強の理学と工学が進展する．一方，半導体光物性的には，低温成長GaAsにおける線形，非線形吸収が定量化され，この材料における非線形光学応答の物理的理解が進む．