Pons-Valencia P, Alfaro-Mozaz F J, Wiecha M M, Biolek V, Dolado I, Vélez S, Li P, Alonso-González P, Casanova F, Hueso L E, Martín-Moreno L, Hillenbrand R, Nikitin A Y
Instituto de Ciencia de Materiales de Aragón and Departamento de Física de la Materia Condensada, CSIC-Universidad de Zaragoza, 50009, Zaragoza, Spain.
CIC nanoGUNE, 20018, Donostia-San Sebastián, Spain.
Nat Commun. 2019 Jul 19;10(1):3242. doi: 10.1038/s41467-019-11143-7.
Launching and manipulation of polaritons in van der Waals materials offers novel opportunities for field-enhanced molecular spectroscopy and photodetection, among other applications. Particularly, the highly confined hyperbolic phonon polaritons (HPhPs) in h-BN slabs attract growing interest for their capability of guiding light at the nanoscale. An efficient coupling between free space photons and HPhPs is, however, hampered by their large momentum mismatch. Here, we show -by far-field infrared spectroscopy, infrared nanoimaging and numerical simulations- that resonant metallic antennas can efficiently launch HPhPs in thin h-BN slabs. Despite the strong hybridization of HPhPs in the h-BN slab and Fabry-Pérot plasmonic resonances in the metal antenna, the efficiency of launching propagating HPhPs in h-BN by resonant antennas exceeds significantly that of the non-resonant ones. Our results provide fundamental insights into the launching of HPhPs in thin polar slabs by resonant plasmonic antennas, which will be crucial for phonon-polariton based nanophotonic devices.
在范德华材料中激发和操控极化激元为场增强分子光谱学、光探测及其他应用带来了新机遇。特别地，六方氮化硼（h-BN）薄片中高度受限的双曲型声子极化激元（HPhPs）因其在纳米尺度上引导光的能力而备受关注。然而，自由空间光子与HPhPs之间的高效耦合受到它们较大动量失配的阻碍。在此，我们通过远场红外光谱、红外纳米成像和数值模拟表明，共振金属天线能够在薄h-BN薄片中高效激发HPhPs。尽管h-BN薄片中的HPhPs与金属天线中的法布里-珀罗等离子体共振存在强烈杂化，但共振天线在h-BN中激发传播型HPhPs的效率显著超过非共振天线。我们的结果为通过共振等离子体天线在薄极性薄片中激发HPhPs提供了基本见解，这对于基于声子极化激元的纳米光子器件至关重要。
