Ermolaev G A, Grudinin D V, Stebunov Y V, Voronin K V, Kravets V G, Duan J, Mazitov A B, Tselikov G I, Bylinkin A, Yakubovsky D I, Novikov S M, Baranov D G, Nikitin A Y, Kruglov I A, Shegai T, Alonso-González P, Grigorenko A N, Arsenin A V, Novoselov K S, Volkov V S
Center for Photonics and 2D Materials, Moscow Institute of Physics and Technology, Dolgoprudny, Russia.
Skolkovo Institute of Science and Technology, Moscow, Russia.
Nat Commun. 2021 Feb 8;12(1):854. doi: 10.1038/s41467-021-21139-x.
Large optical anisotropy observed in a broad spectral range is of paramount importance for efficient light manipulation in countless devices. Although a giant anisotropy has been recently observed in the mid-infrared wavelength range, for visible and near-infrared spectral intervals, the problem remains acute with the highest reported birefringence values of 0.8 in BaTiS and h-BN crystals. This issue inspired an intensive search for giant optical anisotropy among natural and artificial materials. Here, we demonstrate that layered transition metal dichalcogenides (TMDCs) provide an answer to this quest owing to their fundamental differences between intralayer strong covalent bonding and weak interlayer van der Waals interaction. To do this, we made correlative far- and near-field characterizations validated by first-principle calculations that reveal a huge birefringence of 1.5 in the infrared and 3 in the visible light for MoS. Our findings demonstrate that this remarkable anisotropy allows for tackling the diffraction limit enabling an avenue for on-chip next-generation photonics.
在广泛光谱范围内观察到的大光学各向异性对于无数器件中的高效光操纵至关重要。尽管最近在中红外波长范围内观察到了巨大的各向异性，但对于可见光和近红外光谱区间，该问题仍然很严峻，在BaTiS和h-BN晶体中报道的最高双折射值仅为0.8。这个问题激发了人们对天然和人工材料中巨大光学各向异性的深入探索。在此，我们证明层状过渡金属二硫属化物（TMDCs）由于其层内强共价键和层间弱范德华相互作用之间的根本差异，为这一探索提供了答案。为此，我们通过第一性原理计算进行了相关的远场和近场表征，结果显示MoS在红外波段的双折射高达1.5，在可见光波段高达3。我们的研究结果表明，这种显著的各向异性能够突破衍射极限，为片上下一代光子学开辟了一条道路。
