Highly Confined and Tunable Hyperbolic Phonon Polaritons in Van Der Waals Semiconducting Transition Metal Oxides. Issue 13 (22nd February 2018)

• Record Type: Journal Article
• Authors: Zheng, Zebo; Chen, Jianing; Wang, Yu; Wang, Ximiao; Chen, Xiaobo; Liu, Pengyi; Xu, Jianbin; Xie, Weiguang; Chen, Huanjun; Deng, Shaozhi; Xu, Ningsheng
• Is Part Of: Advanced materials. Volume 30:Issue 13(2018)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2018-02-22
• Subjects: hyperbolicity -- mid‐infrared -- phonon polaritons -- transition metal oxides -- vdW materials; Materials -- Periodicals; Chemical vapor deposition -- Periodicals; 620.11
• DOI: 10.1002/adma.201705318
• Languages: English
• ISSNs: 0935-9648

Abstract

Abstract: 2D van der Waals (vdW) layered polar crystals sustaining phonon polaritons (PhPs) have opened up new avenues for fundamental research and optoelectronic applications in the mid‐infrared to terahertz ranges. To date, 2D vdW crystals with PhPs are only experimentally demonstrated in hexagonal boron nitride (hBN) slabs. For optoelectronic and active photonic applications, semiconductors with tunable charges, finite conductivity, and moderate bandgaps are preferred. Here, PhPs are demonstrated with low loss and ultrahigh electromagnetic field confinements in semiconducting vdW α‐MoO3 . The α‐MoO3 supports strong hyperbolic PhPs in the mid‐infrared range, with a damping rate as low as 0.08. The electromagnetic confinements can reach ≈λ0 /120, which can be tailored by altering the thicknesses of the α‐MoO3 2D flakes. Furthermore, spatial control over the PhPs is achieved with a metal‐ion‐intercalation strategy. The results demonstrate α‐MoO3 as a new platform for studying hyperbolic PhPs with tunability, which enable switchable mid‐infrared nanophotonic devices. Abstract : A van der Waals transition metal oxide, α‐MoO3, is demonstrated as a new natural hyperbolic material, which can sustain low‐loss phonon polaritons (PhPs) with ultrahigh electromagnetic confinements in the mid‐infrared region. The α‐MoO3 PhPs can be tailored by either altering the thicknesses of the flake or metal‐ion intercalations.