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[Editors Pick] Current Optics and Photonics Vol. 4 no. 4 (2020 August)

한국광학회 hit 165 date 2021-04-05

Terahertz Generation by a Resonant Photoconductive Antenna
Kanghee Lee1,2, Seong Cheol Lee1, Won Tae Kim1, Jagang Park2, Bumki Min2, and Fabian Rotermund1 *

1 Department of Physics, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea
2 Department of Mechanical Engineering, Korea Advanced Institute of Science and Technology (KAIST), Daejeon 34141, Korea

 

 

 

Current Optics and Photonics  Vol. 4 No. 4 (2020 August) pp. 373-379
DOI: https://doi.org/10.3807/COPP.2020.4.4.373

 


 


Fig. 1  (a) Microscopic images of the NRPCA (top panel) and schematic of its cross-section (bottom). The inset in the top panel presents an enlarged view. The bidirectional arrow indicates the THz field direction for the transmission measurement in (c). (b) Microscopic images of the RPCA (top panel) and schematic of its cross section (bottom). (c) Measured amplitude transmission from the NRPCA. (d) Measured amplitude transmission from the RPCA.

 

 

Abstract

In this study, we investigate terahertz (THz) generation by a photoconductive antenna with electrodes in the shape of split-ring resonators. According to our theoretical investigation based on a lumped-circuit model, the inductance of this electrode structure leads to resonant behavior of the photo-induced current. Hence, near the resonance frequency the spectral components generated by a resonant photoconductive antenna can be greater than those produced by a non-resonant one. For experimental verification, a resonant photoconductive antenna, which possesses a resonance mode at 0.6 THz, and a non-resonant photoconductive antenna with stripe-shaped electrodes were fabricated on a semi-insulating GaAs substrate. The THz generation by both of the photoconductive antennas demonstrated a good agreement with the theoretically expected results. The observed relationship between the resonant electrodes of the photoconductive antenna and the generated THz spectrum can be further employed to design a narrow-band THz source with an on-demand frequency.