Department of Electrical & Computer Engineering , The University of Texas at Austin , Austin , Texas 78712 , United States.
Department of Physics , The University of Texas at Austin , Austin , Texas 78712 , United States.
Nano Lett. 2019 Feb 13;19(2):1009-1014. doi: 10.1021/acs.nanolett.8b04242. Epub 2019 Jan 2.
Highly confined and low-loss hyperbolic phonon polaritons in hexagonal boron nitride possess properties analogous to surface plasmon polaritons, but with enhanced confinement and lower loss. Their properties have been so far mostly studied on dielectric substrates, which provide an asymmetric environment for polariton propagation, and add to damping. In this work, we investigate hyperbolic phonon polaritons over suspended hexagonal boron nitride, showing remarkable properties, including elongated polariton wavelength and reduced damping, up to 18% lower compared to dielectric-backed samples. We use real-space nanoimaging of the polaritons in hexagonal boron nitride to demonstrate and visualize these effects. Our results indicate that suspended boron nitride offers better figures of merit for polariton transport, which are generalizable to other polaritonic materials, and they may be explored in heterostructures for advanced nanophotonic applications.
在六方氮化硼中，高度限制和低损耗的双曲声子极化激元具有类似于表面等离激元的性质，但具有更强的限制和更低的损耗。到目前为止，它们的性质主要是在介电衬底上研究的，介电衬底为极化激元的传播提供了不对称的环境，并增加了阻尼。在这项工作中，我们研究了悬空六方氮化硼中的双曲声子极化激元，展示了显著的性质，包括延长的极化激元波长和减少的阻尼，与介电背底样品相比，阻尼降低了 18%。我们使用六方氮化硼中极化激元的实空间纳米成像来演示和可视化这些效应。我们的结果表明，悬空氮化硼为极化激元输运提供了更好的品质因数，这对于其他极化激元材料是普遍适用的，并且它们可以在异质结构中探索用于先进的纳米光子应用。
