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Plasmonic Nanolasers Enhanced by Hybrid Graphene-Insulator-Metal Structures
(2019-08-01)
Li, Heng
;
Li, Jhu-Hong
;
Hong, Kuo-Bin
;
Yu, Min-Wen
;
Chun, Yi-Cheng
Graphene is a two-dimensional (2D) structure that creates a linear relationship between energy and momentum that not only forms massless Dirac fermions with extremely high group velocity but also exhibits a broadband transmission from 300 to 2500 nm that can be applied to many optoelectronic applications, such as solar cells, light-emitting devices, touchscreens, ultrafast photodetectors, and lasers. Although the plasmonic resonance of graphene occurs in the terahertz band, graphene can be combined with a noble metal to provide a versatile platform for supporting surface plasmon waves. In this study, we propose a hybrid graphene-insulator-metal (GIM) structure that can modulate the surface plasmon polariton (SPP) dispersion characteristics and thus influence the performance of plasmonic nanolasers. Compared with values obtained when graphene is not used on an Al template, the propagation length of SPP waves can be increased 2-fold, and the threshold of nanolasers is reduced by 50% when graphene is incorporated on the template. The GIM structure can be further applied in the future to realize electrical control or electrical injection of plasmonic devices through graphene.
Circularly-polarized lasing of ultraviolet plasmonic gammadion nanocavity
(2019-01-01)
Cheng, Pi-Ju
;
Lai, Ming-Sheng
;
Hsiao, Yu-Hao
;
Yu, Cheng-Li
;
Chang, Chiao-Yun
In this work, we present the model of plasmonic chrial nanolasers composed of aluminum-coated gallium-nitride (GaN) gammadions, which may lase with a high degree of circular polarization at room temperatures. Using the finite-element method, we examine resonant modes of the four-fold rotationally symmetric cavities of gammadions whose resonant frequencies lie in the gain spectrum of GaN. We find a degenerate doublet of resonant modes which can couple to plane waves in the far-field zone above gammadions. Their near-field profiles exhibit localized distribution in the arms of gammadions and a Fabry-Perot standing-wave pattern along the post. In practice, fabrication imperfections would inevitably spoil the four-fold rotation symmetry of gammadions. Typical perturbation could lift the degeneracy of doublet and leads to mixing of the two degenerate modes which may still output signals with observable handedness above gammadions. Considering a gammadion cavity with a single elongated arm, we show that the magnitude of dissymmetry factor of its resonant mode can be larger than unity. Our calculations are consistent with the experimental results, indicating that the right-handed gammadion cavities lase with a magnitude of dissymmetry factors near 1 at a wavelength of 364 nm. The dimensionless effective mode volume scaled by the cube of effective wavelength is 2.62, reflecting a modal distribution remarkably confined in the plasmonic structures and the capability of enhancing the spontaneous-emission rate noticeably. These chiral nanolasers with an ultrasmall footprint could be potentially utilized as future circularly-polarized photon source at the chip level.
High-Operation-Temperature Plasmonic Nanolasers on Single-Crystalline Aluminum
(2016-05)
Chou, Yu-Hsun
;
Wu, Yen-Mo
;
Hong, Kuo-Bin
;
Chou, Bo-Tsun
;
Shih, Jheng-Hong
The recent development of plasmonics has overcome the optical diffraction limit and fostered the development of several important components including nanolasers, low-operation-power modulators, and high-speed detectors. In particular, the advent of surface-plasmon-polariton (SPP) nanolasers has enabled the development of coherent emitters approaching the nanoscale. SPP nanolasers widely adopted metal insulator semiconductor structures because the presence of an insulator can prevent large metal loss. However, the insulator is not necessary if permittivity combination of laser structures is properly designed. Here, we experimentally demonstrate a SPP nanolaser with a ZnO nanowire on the as-grown single-crystalline aluminum. The average lasing threshold of this simple structure is 20 MW/cm(2), which is four-times lower than that of structures with additional insulator layers. Furthermore, single-mode laser operation can be sustained at temperatures up to 353 K. Our study represents a major step toward the practical realization of SPP nanolasers.
High-operation-temperature Aluminum-based SPP Nanolasers
(2016)
Chou, Yu-Hsun
;
Hong, Kuo-Bin
;
Chou, Bo-Tsun
;
Wu, Yen-Mo
;
Shih, Jheng-Hong
Metal-insulator-semiconductor structures has widely adopted in plasmonics lasers. However, we found that the insulator is not necessary if permittivity combination of laser structures is properly designed. Single-mode laser operation was demonstrate in devices without artificial insulator layers. Moreover, the operation temperature can achieve to 353 K.

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