Ultralow-Loss Phonon Polaritons in the Isotope-Enriched α-MoO3

Yongqian Zhao; Jiancui Chen; Mengfei Xue; Runkun Chen; Shangtong Jia; Jianjun Chen; Lihong Bao; Hong-Jun Gao; Jianing Chen

doi:10.1021/acs.nanolett.2c03742

Ultralow-Loss Phonon Polaritons in the Isotope-Enriched α-MoO₃

Nano Lett. 2022 Dec 28;22(24):10208-10215. doi: 10.1021/acs.nanolett.2c03742. Epub 2022 Nov 7.

Authors

Yongqian Zhao^{1

2}, Jiancui Chen^{1

2}, Mengfei Xue^{1

2

3}, Runkun Chen^{1

2}, Shangtong Jia⁴, Jianjun Chen^{5

4

6}, Lihong Bao^{1

2

7}, Hong-Jun Gao^{1

2

7}, Jianing Chen^{1

2

7}

Affiliations

¹ Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences Beijing 100190, China.
² School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China.
³ Wenzhou Institute, University of Chinese Academy of Sciences, Wenzhou 325001, China.
⁴ State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University, Beijing 100871, China.
⁵ Department of Physics and Applied Optics Beijing Area Major Laboratory, Beijing Normal University, Beijing 100875, China.
⁶ Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan, Shanxi 030006, China.
⁷ Songshan Lake Materials Laboratory, Dongguan, Guangdong 523808, China.

PMID: 36343338
DOI: 10.1021/acs.nanolett.2c03742

Abstract

α-MoO₃, a natural van der Waals (vdWs) material, has received wide attention in nano-optics for supporting highly confined anisotropic phonon polaritons (PhPs) from the mid-infrared to the terahertz region, which opens a new route for manipulating light at the nanoscale. However, its optical loss hinders light manipulation with high efficiency. This work demonstrates that the isotope-enriched Mo element enables ultralow-loss PhPs in the α-MoO₃. Raman spectra reveal that the isotope-enriched Mo element in the α-MoO₃ allows different optical phonon frequencies by efficiently altering the Reststrahlen band's dispersion. The Mo isotope-enriched α-MoO₃ significantly reduces the PhPs' optical loss due to efficient optical coherence, which enhances the propagation length revealed by infrared nanoimaging. These findings suggest that the isotope-enriched α-MoO₃ is a new feasible 2D material with an ultralow optical loss for possible high-performance integrated photonics and quantum optics devices.

Keywords: hyperbolic materials; near-field imaging; phonon polaritons; van der Waals materials.