ナノスケールで光を操り、光子のアップコンバージョンを高める(Manipulating light at nanoscale for increased photon upconversion)

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2024-02-22 シンガポール国立大学(NUS)

NUSの化学部門のLiu Xiaogang教授を中心とする研究チームは、イタリア国立研究評議会のGianluigi Zito博士との共同で、「超臨界結合」と呼ばれる特殊な光学現象を発見しました。この発見は、光子のアップコンバージョン効率を数桁向上させ、光を操作する新たな手法を開拓し、量子コンピューティング、超解像イメージング、レーザーや光共振器などの光子デバイスの開発を推進する可能性があります。この研究成果は2024年2月22日に『Nature』誌に掲載されました。

<関連情報>

連続体の超臨界束縛状態による巨大アップコンバージョンを直接観測 Directive giant upconversion by supercritical bound states in the continuum

Chiara Schiattarella,Silvia Romano,Luigi Sirleto,Vito Mocella,Ivo Rendina,Vittorino Lanzio,Fabrizio Riminucci,Adam Schwartzberg,Stefano Cabrini,Jiaye Chen,Liangliang Liang,Xiaogang Liu & Gianluigi Zito
Nature  Published:21 February 2024
DOI:https://doi.org/10.1038/s41586-023-06967-9

ナノスケールで光を操り、光子のアップコンバージョンを高める(Manipulating light at nanoscale for increased photon upconversion)

Abstract

Photonic bound states in the continuum (BICs), embedded in the spectrum of free-space waves1,2 with diverging radiative quality factor, are topologically non-trivial dark modes in open-cavity resonators that have enabled important advances in photonics3,4. However, it is particularly challenging to achieve maximum near-field enhancement, as this requires matching radiative and non-radiative losses. Here we propose the concept of supercritical coupling, drawing inspiration from electromagnetically induced transparency in near-field coupled resonances close to the Friedrich–Wintgen condition2. Supercritical coupling occurs when the near-field coupling between dark and bright modes compensates for the negligible direct far-field coupling with the dark mode. This enables a quasi-BIC field to reach maximum enhancement imposed by non-radiative loss, even when the radiative quality factor is divergent. Our experimental design consists of a photonic-crystal nanoslab covered with upconversion nanoparticles. Near-field coupling is finely tuned at the nanostructure edge, in which a coherent upconversion luminescence enhanced by eight orders of magnitude is observed. The emission shows negligible divergence, narrow width at the microscale and controllable directivity through input focusing and polarization. This approach is relevant to various physical processes, with potential applications for light-source development, energy harvesting and photochemical catalysis.

1700応用理学一般
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