Theory of Optical Nonlocality in Polar Dielectrics

Abstract

Sub-wavelength confinement of mid-infrared light can be achieved exploiting the metal-like optical response of polar dielectric crystals in their Reststrahlen spectral region, where they support evanescent modes termed surface phonon polaritons. In the past few years the investigation of phonon polaritons localised in nanoresonators and layered heterostructures has enjoyed remarkable success, highlighting them as a promising platform for mid-infrared nanophotonic applications. Here we prove that the standard local dielectric description of phonon polaritons in nanometric objects fails due to the nonlocal nature of the phonon response and we develop the corresponding nonlocal theory. Application of our general theory to both dielectric nanospheres and thin films demonstrates that polar dielectrics exhibit a rich nonlocal phenomenology, qualitatively different from the one of plasmonic systems, due to the negative dispersion of phononic optical modes.

arXiv comment13 pages, 6 figures

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Cited by in corpus (16)

• Perspective: Phonon polaritons for infrared optoelectronics
• Berreman Embedded Eigenstates for Narrowband Absorption and Thermal Emission
• Roadmap on Nonlocality in Photonic Materials and Metamaterials
• Chiral Polaritonics: Analytic Solutions, Intuition and its Use
• A general framework of canonical quasinormal mode analysis for extreme nano-optics
• Nonlocal Scattering Matrix Description of Anisotropic Polar Heterostructures
• Semiconductor quantum plasmonics
• Atomistic modeling of extreme near-field heat transport across nanogaps between two polar dielectric materials
• An engineered planar plasmonic reflector for polaritonic mode confinement
• Exact solution of polaritonic systems with arbitrary light and matter frequency-dependent losses
• Polaritonic quantisation in nonlocal polar material
• Radiative heat exchange driven by acoustic vibration modes between two solids at the atomic scale
• Lighting of a monochromatic scatterer with virtual gain
• Revisit of generalized Kerker's conditions using composite metamaterials
• The Uniqueness Theorem for Nonlocal Hydrodynamic Media
• Prospects to bypass nonlocal phenomena in metals using phonon-polaritons