Abstract-Bias field tailored plasmonic nano-electrode for high-power terahertz photonic devices

Kiwon Moon

, Il-Min Lee

, Jun-Hwan Shin

, Eui Su Lee

, Namje Kim

, Won-Hui Lee

, Hyunsung Ko

, Sang-Pil Han

 & Kyung Hyun Park

• • http://www.nature.com/articles/srep13817

• Scientific Reports 5, Article number: 13817 (2015)
• doi:10.1038/srep13817

Photoconductive antennas with nano-structured electrodes and which show significantly improved performances have been proposed to satisfy the demand for compact and efficient terahertz (THz) sources. Plasmonic field enhancement was previously considered the dominant mechanism accounting for the improvements in the underlying physics. However, we discovered that the role of plasmonic field enhancement is limited and near-field distribution of bias field should be considered as well. In this paper, we clearly show that the locally enhanced bias field due to the size effect is much more important than the plasmonic enhanced absorption in the nano-structured electrodes for the THz emitters. Consequently, an improved nano-electrode design is presented by tailoring bias field distribution and plasmonic enhancement. Our findings will pave the way for new perspectives in the design and analysis of plasmonic nano-structures for more efficient THz photonic devices.

Abstract-Food inspection system using terahertz imaging

1. Won-Hui Lee^*, 
2. Wangjoo Lee

Article first published online: 11 MAR 2014

DOI: 10.1002/mop.28303

Copyright © 2014 Wiley Periodicals, Inc.

http://onlinelibrary.wiley.com/doi/10.1002/mop.28303/abstract

A terahertz (THz) transmission imaging system using a 0.2 and 0.4 THz gyrotron as a high power source was evaluated. In the gyrotron, 0.2 THz is the first main mode and 0.4 THz is the second harmonic mode. The output power of gyrotron is about 100 W at 0.2 THz and 1 W at 0.4 THz. For fast imaging, the source output was shaped into a line beam and an array detector was used. Two reflecting mirrors were utilized for a reflective imaging system. A 0.8 mm resolution was obtained using a 0.4 THz transmission image. The feasibility of fast THz imaging for the inspection of foreign substances in food is demonstrated. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:1211–1214, 2014