Leonid Gilburd

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Surface polaritons, which are electromagnetic waves coupled to material charge oscillations, have enabled applications in concentrating, guiding and harvesting optical energy below the diffraction limit. Surface plasmon polaritons involve oscillations of electrons and are accessible in noble metals at visible and near-infrared wavelengths, whereas surface(More)
Boron nitride (BN) is considered to be a promising substrate for graphene-based devices in part because its large band gap can serve to insulate graphene in layered heterostructures. At mid-infrared frequencies, graphene supports surface plasmon polaritons (SPPs), whereas hexagonal-BN (h-BN) is found to support surface phonon polaritons (SPhPs). We report(More)
Hexagonal boron nitride (hBN) is a 2D material that supports traveling waves composed of material vibrations and light, and is attractive for nanoscale optical devices that function in the infrared. However, the only current method of launching these traveling waves requires the use of a metal nanostructure. Here, we show that the polaritonic waves can be(More)
Surface phonon modes are lattice vibrational modes of a solid surface. Two common surface modes, called longitudinal and transverse optical modes, exhibit lattice vibration along or perpendicular to the direction of the wave. We report a two-color, infrared pump-infrared probe technique based on scattering type near-field optical microscopy (s-SNOM) to(More)
Surface phonon-polariton (SPhP) modes exist under optical excitation of polar materials, and are accessible using scattering type near-field optical microscopy (s-SNOM). Hexagonal boron nitride (hBN) and boron nitride nanotubes (BNNTs) can exhibit such modes under IR excitation, in spectral regions where the permittivity is negative. Herein we present(More)
In order to apply the ability of hexagonal boron nitride (hBN) to confine energy in the form of hyperbolic phonon polariton (HPhP) modes in photonic-electronic devices, approaches to finely control and leverage the sensitivity of these propagating waves must be investigated. Here, we show that by surrounding hBN with materials of lower/higher dielectric(More)
We report experimental observations of optical hot-spots associated with surface phonon polaritons in boron nitride nanotubes. As revealed by near-field optical microscopy, the hot-spots have mode volumes as small as ≃2.7×10-6λ03 (λ0 is the wavelength of the exciting light in vacuum), which are in the deep subwavelength regime. Such strong light-trapping(More)
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