Ultra-low-loss Polaritons in Isotopically Pure Materials: A New Approach

摘要

Conventional optical components are limited to size-scales much larger thanthe wavelength of light, as changes in the amplitude, phase and polarization ofthe electromagnetic fields are accrued gradually along an optical path.However, advances in nanophotonics have produced ultra-thin, co-called "flat"optical components that beget abrupt changes in these properties over distancessignificantly shorter than the free space wavelength. While high optical lossesstill plague many approaches, phonon polariton (PhP) materials havedemonstrated long lifetimes for sub-diffractional modes in comparison toplasmon-polariton-based nanophotonics. We experimentally observe a three-foldimprovement in polariton lifetime through isotopic enrichment of hexagonalboron nitride (hBN). Commensurate increases in the polariton propagation lengthare demonstrated via direct imaging of polaritonic standing waves by means ofinfrared nano-optics. Our results provide the foundation for amaterials-growth-directed approach towards realizing the loss control necessaryfor the development of PhP-based nanophotonic devices.