A comparative study of the plasmon effect in nanoelectrode THz emitters: Pulse vs. continuous-wave radiation

Plasmonic field enhancement in terahertz (THz) generation is one of the recently arisen techniques in the THz field that has attracted considerable interest. However, the reported levels of enhancement of THz output power in the literature are significantly different from each other, from less than...

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Bibliographic Details
Published in:Applied physics letters 2016-08, Vol.109 (7)
Main Authors: Moon, Kiwon, Lee, Eui Su, Choi, Jeongyong, Lee, Donghun, Lee, Il-Min, Han, Sang-Pil, Kim, Hyun-Soo, Park, Kyung Hyun
Format: Article
Language:English
Subjects:
Applied physics
CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS
Comparative studies
Continuous radiation
EFFICIENCY
ELECTRODES
Emitters
Nanostructure
NANOSTRUCTURES
OPTOELECTRONIC DEVICES
PLASMONS
Pulsed radiation
PULSES
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Summary:Plasmonic field enhancement in terahertz (THz) generation is one of the recently arisen techniques in the THz field that has attracted considerable interest. However, the reported levels of enhancement of THz output power in the literature are significantly different from each other, from less than two times to about two orders of magnitude of enhancement in power, which implies the existence of other major limiting factors yet to be revealed. In this work, the contribution of the plasmonic effect to the power enhancement of THz emitters is revisited. We show that the carrier collection efficiency in a THz emitter with plasmonic nanostructures is more critical to the device performance than the plasmonic field enhancement itself. The strong reverse fields induced by the highly localized plasmonic carriers in the vicinity of the nanoelectrodes screen the carrier collections and seriously limit the power enhancement. This is supported by our experimental observations of the significantly enhanced power in a plasmonic nanoelectrode THz emitter in continuous-wave radiation mode, while the same device has limited enhancement with pulsed radiation. We hope that our study may provide an intuitive but practical guideline in adopting plasmonic nanostructures with an aim of enhancing the efficiency of optoelectronic devices.
ISSN:0003-6951
1077-3118
DOI:10.1063/1.4961305