Phonon polaritons, hybrid light-matter quasiparticles resulting from strong coupling of the electromagnetic field with the lattice vibrations of polar crystals are a promising platform for mid-infrared photonics but for the moment there has been no proposal allowing for their electrical pumping. Electrical currents in fact mainly generate longitudinal optical phonons, while only transverse ones participate in the creation of phonon polaritons. We demonstrate how to exploit long-cell polytypes of silicon carbide to achieve strong coupling between transverse phonon polaritons and zone-folded longitudinal optical phonons. We develop a microscopic theory predicting the existence of the resulting hybrid longitudinal-transverse excitations. We then provide an experimental observation by tuning the resonance of a nanopillar array through the folded longitudinal optical mode, obtaining a clear spectral anti-crossing. The hybridisation of phonon polaritons with longitudinal phonons could represent an important step toward the development of phonon polariton-based electrically pumped mid-infrared emitters.
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http://dx.doi.org/10.1038/s41467-019-09414-4 | DOI Listing |
Discov Nano
January 2025
LIMMS, CNRS-IIS IRL 2820, The University of Tokyo, Tokyo, 153-8505, Japan.
We demonstrate unprecedented control and enhancement of thermal radiation using subwavelength conical membranes of silicon nitride. Based on fluctuational electrodynamics, we find that the focusing of surface phonon-polaritons along these membranes enhances their far-field thermal conductance by three orders of magnitude over the blackbody limit. Our calculations reveal a non-monotonic dependence of the thermal conductance on membrane geometry, with a characteristic radiation plateau emerging at small front widths due to competing effects of the polariton focusing and radiative area.
View Article and Find Full Text PDFNanophotonics
January 2025
Departamento de Ingeniería Electrónica, E.T.S.I. de Telecomunicación, Instituto de Sistemas Optoelectrónicos y Microtecnología (ISOM), Universidad Politécnica de Madrid, Madrid, 28040 Spain.
Polar biaxial crystals with extreme anisotropy hold promise for the spatial control and the manipulation of polaritons, as they can undergo topological transitions. However, taking advantage of these unique properties for nanophotonic devices requires to find mechanisms to modulate dynamically the material response. Here, we present a study on the propagation of surface phonon polaritons (SPhPs) in a photonic architecture based on a thin layer of α-MoO deposited on a semiconducting 4H-SiC substrate, whose carrier density can be tuned through photoinduction.
View Article and Find Full Text PDFNano Lett
January 2025
Department of Chemistry, University of Rochester, Rochester, New York 14627, United States.
Recent experiments have shown that exciton transport can be significantly enhanced through hybridization with confined photonic modes in a cavity. The light-matter hybridization generates exciton-polariton (EP) bands, whose group velocity is significantly larger than the excitons. Dissipative mechanisms that affect the constituent states of EPs, such as exciton-phonon coupling and cavity loss, have been observed to reduce the group velocities in experiments.
View Article and Find Full Text PDFNano Lett
January 2025
Department of Physics, University of Oviedo, Oviedo 33006, Spain.
Polaritons are central to the development of nanophotonics, as they provide mechanisms for manipulating light at the nanoscale. A key advancement has been the demonstration of polariton canalization in which the energy flow is directed along a single direction. An intriguing case is the canalization of ray polaritons, characterized by an enhanced density of optical states.
View Article and Find Full Text PDFJ Chem Phys
January 2025
Department of Chemistry, Columbia University, New York, New York 10027, USA.
In this work, we investigate anharmonic vibrational polaritons formed due to strong light-matter interactions in an optical cavity between radiation modes and anharmonic vibrations beyond the long-wavelength limit. We introduce a conceptually simple description of light-matter interactions, where spatially localized cavity radiation modes couple to localized vibrations. Within this theoretical framework, we employ self-consistent phonon theory and vibrational dynamical mean-field theory to efficiently simulate momentum-resolved vibrational-polariton spectra, including effects of anharmonicity.
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