Abstract-Enhanced Confinement of Terahertz Surface Plasmon Polaritons in Bulk Dirac Semimetal-Insulator-Metal Waveguides

Yi Su, Qi Lin, Xiang Zhal, Ling-Ling Wang

https://nanoscalereslett.springeropen.com/articles/10.1186/s11671-018-2686-z

A subwavelength terahertz plasmonic waveguide based on bulk Dirac semimetal (BDS)-insulator-metal (BIM) structure is investigated, which indicates that there is an optimized frequency range with the better confinement as well as lower loss. A broadband mode confinement up to λ0/15 with a relatively low loss of 1.0 dB/λ0 can be achieved. We also show that two silicon ribbons introduced into the BIM waveguide can form a dynamically tunable filter tailoring terahertz surface plasmon polaritons in deep-subwavelength scale, which can be further exploited for the design of ultra-compact THz plasmonic devices with dynamical tunability. Our results may also provide potential applications in optical filtering.

Abstract-Giant field enhancements in ultrathin nanoslots above 1 terahertz

Dasom Kim, Jeeyoon Jeong, Geunchang Choi, Young-Mi Bahk, Taehee Kang, Dukhyung Lee, Bidhek Thusa, Dai-Sik Kim,

https://pubs.acs.org/doi/abs/10.1021/acsphotonics.8b00151?journalCode=apchd5

Strong demand for plasmonic devices with an enormously enhanced electric field and desired resonance frequencies has led to extensive investigations of metallic slot structures. While strong field enhancement can be achieved by reducing the width of the slot, the effect of the gap surface plasmon limits the maximum achievable field enhancement at higher frequencies. Specifically, the effect of the gap surface plasmon becomes stronger as the gap width decreases and strongly suppresses the transmission while causing a red-shift of the resonance. Here, we overcome these issues and realize strong field enhancements at higher frequencies, by managing the metal thickness of the nanoslots. We show that as the nanoslots become as thin as 10 nm, they show a giant electric field enhancement of up to 7600. Moreover, the resonances are strongly blue-shifted to above 1 THz from 0.33 THz. Our work provides a novel route to achieving high field enhancements at desired frequencies, as well as a means by which to characterize the slot as the gap-sensitive or substrate-sensitive type

Abstract-Direct modeling of near field thermal radiation in a metamaterial

Dawei Lu, Ananda Das, and Wounjhang Park

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-11-12999&origin=search

The study of near field thermal radiation is gaining renewed interest thanks in part to their great potential in energy harvesting applications. It is well known that plasmonic or polaritonic materials exhibit strongly enhanced fields near the surface, but it is not trivial to quantitatively predict their impact on thermal radiation intensity in the near field. In this paper, we present a case study for a metamaterial that supports a surface plasmon mode in the terahertz region and consequently exhibits strongly enhanced near field thermal radiation at the plasmon resonance frequency. We implemented a finite-difference time-domain method that thermally excites the metamaterial with randomly fluctuating dipoles according to the fluctuation-dissipation theorem. The calculated thermal radiation from the metamaterial was then compared with the case of optical excitation by the plane wave incident on the metamaterial surface. The optical excitation couples only to the mode that satisfies the momentum matching condition while thermal excitation is not bound by it. As a result, the near field thermal radiation exhibits substantial differences compared to the optically excited surface plasmon modes. Under thermal excitation, the near field intensity at 1 µm away from metal surface of the metamaterial reaches a maximum enhancement of 43 fold over the far field at the frequency of the Brillouin zone boundary mode while the near field intensity under optical excitation reaches a maximum enhancement of 24 fold at the frequency of the Brillouin zone center mode. In addition, the peak near field intensity under thermal excitation shows a 4-fold enhancement over blackbody radiation with linear polarization radiation in the far field. The ability to precisely predict the local field intensity under thermal excitation is critical to the development of advanced energy devices that take advantage of this near field enhancement and could lead to the development of new generation of novel energy technology.

© 2017 Optical Society of America

Abstract-Realization of 3D Metamaterial and Plasmonic Devices at Optical Frequencies

Junsuk Rho

https://www.osapublishing.org/abstract.cfm?uri=fio-2017-FTh2D.1&origin=search

I will discuss recent development of fabrication for three-dimensional metamaterials based on two different approaches. The examples include 3D chiral metamaterials (at terahertz and infrared) and self-assembled 3D chiral materials.

© 2017 OSA