Hyperbolic phonon-polaritons in boron nitride for near-field optical imaging and focusing
Abstract
Hyperbolic materials exhibit sub-diffractional, highly directional, volume-confined polariton modes. Here we report that hyperbolic phonon polaritons allow for a flat slab of hexagonal boron nitride to enable exciting near-field optical applications, including unusual imaging phenomenon (such as an enlarged reconstruction of investigated objects) and sub-diffractional focusing. Both the enlarged imaging and the super-resolution focusing are explained based on the volume-confined, wavelength dependent propagation angle of hyperbolic phonon polaritons. With advanced infrared nanoimaging techniques and state-of-art mid-infrared laser sources, we have succeeded in demonstrating and visualizing these unexpected phenomena in both Type I and Type II hyperbolic conditions, with both occurring naturally within hexagonal boron nitride. These efforts have provided a full and intuitive physical picture for the understanding of the role of hyperbolic phonon polaritons in near-field optical imaging, guiding, and focusing applications.
- Publication:
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Nature Communications
- Pub Date:
- June 2015
- DOI:
- 10.1038/ncomms8507
- arXiv:
- arXiv:1502.04093
- Bibcode:
- 2015NatCo...6.7507L
- Keywords:
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- Condensed Matter - Materials Science;
- Physics - Optics
- E-Print:
- Nature Communications, 6, 7507 (2015)