Stable, high-performance sodium-based plasmonic devices in the near infrared

• Published in: Nature (London) Vol. 581; no. 7809; pp. 401 - 405
• Main Authors: Wang, Yang, Yu, Jianyu, Mao, Yi-Fei, Chen, Ji, Wang, Suo, Chen, Hua-Zhou, Zhang, Yi, Wang, Si-Yi, Chen, Xinjie, Li, Tao, Zhou, Lin, Ma, Ren-Min, Zhu, Shining, Cai, Wenshan, Zhu, Jia
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01-05-2020; Nature Publishing Group
• Subjects: 132/122; 140/125; 142/126; 639/301; 639/624; Chemical properties; Devices; Humanities and Social Sciences; I.R. radiation; Image resolution; Light diffraction; Materials; Metals; Metamaterials; multidisciplinary; Near infrared radiation; Near infrared spectroscopy; Noble metals; Optical films; Oscillations; Plasmonics; Polaritons; Propagation; Room temperature; Scanning electron microscopy; Science; Science (multidisciplinary); Silver; Sodium; Spin coating; Surface plasmon resonance sensors; Wave propagation; Waveguides; Wavelengths; China
• ISSN: 0028-0836; 1476-4687
• DOI: 10.1038/s41586-020-2306-9

Plasmonics enables the manipulation of light beyond the optical diffraction limit
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and may therefore confer advantages in applications such as photonic devices
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, optical cloaking
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, biochemical sensing
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and super-resolution imaging
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. However, the essential field-confinement capability of plasmonic devices is always accompanied by a parasitic Ohmic loss, which severely reduces their performance. Therefore, plasmonic materials (those with collective oscillations of electrons) with a lower loss than noble metals have long been sought
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. Here we present stable sodium-based plasmonic devices with state-of-the-art performance at near-infrared wavelengths. We fabricated high-quality sodium films with electron relaxation times as long as 0.42 picoseconds using a thermo-assisted spin-coating process. A direct-waveguide experiment shows that the propagation length of surface plasmon polaritons supported at the sodium–quartz interface can reach 200 micrometres at near-infrared wavelengths. We further demonstrate a room-temperature sodium-based plasmonic nanolaser with a lasing threshold of 140 kilowatts per square centimetre, lower than values previously reported for plasmonic nanolasers at near-infrared wavelengths. These sodium-based plasmonic devices show stable performance under ambient conditions over a period of several months after packaging with epoxy. These results indicate that the performance of plasmonic devices can be greatly improved beyond that of devices using noble metals, with implications for applications in plasmonics, nanophotonics and metamaterials.
A thermo-assisted spin-coating process followed by packaging is used to fabricate sodium films that are stable for several months, enabling the realization of plasmonic devices with state-of-the-art performance at near-infrared wavelengths.