Nanofocusing of Hyperbolic Phonon Polaritons in a Tapered Boron Nitride Slab

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• 作者：Alexey Yu. Nikitin ; Edward Yoxall ; Martin Schnell ; Saül Vélez ; Irene Dolado ; Pablo Alonso-Gonzalez ; Fèlix Casanova ; Luis E. Hueso ; Rainer Hillenbrand
• 刊名：ACS Photonics
• 出版年：2016
• 出版时间：June 15, 2016
• 年：2016
• 卷：3
• 期：6
• 页码：924-929
• 全文大小：531K
• 年卷期：0
• ISSN：2330-4022

文摘

Nanofocusing of light offers new technological opportunities for the delivery and manipulation of electromagnetic fields at subdiffraction-limited length scales. Here, we show that hyperbolic phonon polariton (HPP) modes in the mid-infrared as supported by a hexagonal boron nitride (h-BN) slab can be nanofocused (i.e., both field enhanced and wavelength compressed) by propagation along a vertical taper. Via numerical simulations, we demonstrate that field enhancement factors of 90—for steep tapers—and wavelength compression of more than an order of magnitude—for adiabatic tapers—can be expected. Employing scattering-type scanning near-field optical microscopy, we provide, for the first time, proof-of-principle experimental evidence of a significant HPP wavelength compression. We expect these functionalities to provide diverse applications, from biosensing and nonlinear optics to optical circuitry.