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

Moon K, Lee IM, Shin JH, Lee ES, Kim N, Lee WH, Ko H, Han SP, Park KH - Sci Rep (2015)

Bottom Line: 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.Our findings will pave the way for new perspectives in the design and analysis of plasmonic nano-structures for more efficient THz photonic devices.

View Article: PubMed Central - PubMed

Affiliation: THz Photonics Creative Research Center, Future Research Creative Laboratory, Electronics and Telecommunications Research Institute (ETRI), Daejeon 305-700, Korea.

ABSTRACT
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.

No MeSH data available.


Optical near-field distribution within the GaAs substrate: (a) /Ez/ distributions for both polarizations. (b) /Ex + Ey/ distributions for both polarizations. (c) Bias field distribution.
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f3: Optical near-field distribution within the GaAs substrate: (a) /Ez/ distributions for both polarizations. (b) /Ex + Ey/ distributions for both polarizations. (c) Bias field distribution.

Mentions: The calculated field distributions on the x-y plane at 10 nm beneath the surface of the GaAs are shown in Fig. 3. It is hard to strictly distinguish the plasmonic field distribution and the ordinary optical field distribution from the numerical simulation results. But by noting that the plasmonic effect induces the strong electric field normal to the metallic surface, we could infer the distribution of plasmonic field, or plasmonic carriers from the /Ez/ distribution shown in Fig. 3 (a). The /Ex + Ey/ distribution, shown in Fig. 3(b), collectively shows the plasmonic field and the normal field distribution near to the nano-fingers. In the most area of absorption region of the NE structure, however, the distribution is not related to the plasmonic effect which is clearly confirmed by the negligible /Ez/ within the region. Therefore, /Ex + Ey/ distribution within the intrinsic region of the NE structure can be asymptotically regarded as the ordinary photo-carrier, or at least ordinary photo carrier-dominant, distribution.


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

Moon K, Lee IM, Shin JH, Lee ES, Kim N, Lee WH, Ko H, Han SP, Park KH - Sci Rep (2015)

Optical near-field distribution within the GaAs substrate: (a) /Ez/ distributions for both polarizations. (b) /Ex + Ey/ distributions for both polarizations. (c) Bias field distribution.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4561887&req=5

f3: Optical near-field distribution within the GaAs substrate: (a) /Ez/ distributions for both polarizations. (b) /Ex + Ey/ distributions for both polarizations. (c) Bias field distribution.
Mentions: The calculated field distributions on the x-y plane at 10 nm beneath the surface of the GaAs are shown in Fig. 3. It is hard to strictly distinguish the plasmonic field distribution and the ordinary optical field distribution from the numerical simulation results. But by noting that the plasmonic effect induces the strong electric field normal to the metallic surface, we could infer the distribution of plasmonic field, or plasmonic carriers from the /Ez/ distribution shown in Fig. 3 (a). The /Ex + Ey/ distribution, shown in Fig. 3(b), collectively shows the plasmonic field and the normal field distribution near to the nano-fingers. In the most area of absorption region of the NE structure, however, the distribution is not related to the plasmonic effect which is clearly confirmed by the negligible /Ez/ within the region. Therefore, /Ex + Ey/ distribution within the intrinsic region of the NE structure can be asymptotically regarded as the ordinary photo-carrier, or at least ordinary photo carrier-dominant, distribution.

Bottom Line: 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.Our findings will pave the way for new perspectives in the design and analysis of plasmonic nano-structures for more efficient THz photonic devices.

View Article: PubMed Central - PubMed

Affiliation: THz Photonics Creative Research Center, Future Research Creative Laboratory, Electronics and Telecommunications Research Institute (ETRI), Daejeon 305-700, Korea.

ABSTRACT
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.

No MeSH data available.