233 citations · 1.3k across the 39 of their papers we have counts for
24 papers · 1 filter
Nonlocal-nonlinear phonon polaritons
Gonzalo Álvarez-Pérez, Line Jelver, Alexander Paarmann +1
When light is confined to deeply subwavelength volumes, optical responses can become nonlocal. Yet how nonlocality reshapes nonlinear light-matter interactions remains largely unex…
In-plane vector-field imaging of propagating surface phonon polaritons
Richarda Niemann, Dorothée S. Mader, Gonzalo Alvarez-Pérez +9
Polariton interferometry through optical near-field microscopy has become a powerful tool in nanophotonics, enabling direct spatial access to the propagation characteristics of str…
Ultrafast Nano-Imaging and Optical Control of Hyperbolic Phonon Polaritons at hBN/WS Heterojunctions
Kazuki Kamada, Keisuke Shinokita, Fanyu Zeng +7
Manipulating nanoscale light-matter interactions on ultrafast time scales is indispensable for future polaritonic devices. Hyperbolic phonon polaritons (HPhPs) in van der Waals mat…
Spectral tuning of hyperbolic shear polaritons in monoclinic gallium oxide via isotopic substitution
Giulia Carini, Mohit Pradhan, Elena Gelzinyte +26
Hyperbolic phonon polaritons - hybridized modes arising from the ultrastrong coupling of infrared light to strongly anisotropic lattice vibrations in uniaxial or biaxial polar crys…
Ultraconfined THz Phonon Polaritons in Hafnium Dichalcogenides
R. A. Kowalski, N. S. Mueller, G. Álvarez-Pérez +18
The confinement of electromagnetic radiation to subwavelength scales relies on strong light-matter interactions. In the infrared (IR) and terahertz (THz) spectral ranges, phonon po…
Visualization of topological shear polaritons in gypsum thin films
Pablo Díaz-Núñez, Christian Lanza, Ziwei Wang +10
Low symmetry crystals have recently emerged as a platform for exploring novel light-matter interactions in the form of hyperbolic shear polaritons. These excitations exhibit unique…
Surface Phonon Polariton Ellipsometry
Giulia Carini, Richarda Niemann, Niclas Sven Mueller +2
Surface phonon polaritons (SPhPs) have become a key ingredient for infrared nanophotonics, owing to their long lifetimes and the large number of polar dielectric crystals supportin…
Electro-Optic Cavities for In-Situ Measurement of Cavity Fields
Michael S. Spencer, Joanna M. Urban, Maximilian Frenzel +5
Cavity electrodynamics offers a unique avenue for tailoring ground-state material properties, excited-state engineering, and versatile control of quantum matter. Merging these conc…
Sum-Frequency Generation Spectro-Microscopy in the Reststrahlen Band of Wurtzite-type Aluminum Nitride
Dorothée S. Mader, Richarda Niemann, Martin Wolf +2
Nonlinear-optical microscopy and spectroscopy provide detailed spatial and spectroscopic contrast, specifically sensitive to structural symmetry and order. Ferroics, in particular,…
Unidirectional Ray Polaritons in Twisted Asymmetric Stacks
J. Álvarez-Cuervo, M. Obst, S. Dixit +25
The vast repository of van der Waals (vdW) materials supporting polaritons offers numerous possibilities to tailor electromagnetic waves at the nanoscale. The development of twisto…
Extreme light confinement and control in low-symmetry phonon-polaritonic crystals
Emanuele Galiffi, Giulia Carini, Xiang Ni +9
Polaritons are a hybrid class of quasiparticles originating from the strong and resonant coupling between light and matter excitations. Recent years have witnessed a surge of inter…
Spectroscopic and Interferometric Sum-Frequency Imaging of Strongly Coupled Phonon Polaritons in SiC Metasurfaces
Richarda Niemann, Niclas S. Mueller, Sören Wasserroth +4
Phonon polaritons enable waveguiding and localization of infrared light with extreme confinement and low losses. The spatial propagation and spectral resonances of such polaritons…
Layer-Resolved Resonance Intensity of Evanescent Polariton Modes in Anisotropic Multilayers
Nikolai Christian Passler, Giulia Carini, Dmitry N. Chigrin +1
Phonon polariton modes in layered anisotropic heterostructures are a key building block for modern nanophotonic technologies. The light-matter interaction for evanescent excitation…
Second Harmonic Generation from Grating-Coupled Hybrid Plasmon-Phonon Polaritons
Marcel Kohlmann, Christian Denker, Nikolai C. Passler +4
Polaritons can provide strong optical field enhancement allowing to boost light-matter interaction. Here, we experimentally observe enhancement of mid-infrared second-harmonic gene…
Infrared super-resolution wide-field microscopy using sum-frequency generation
Richarda Niemann, Sören Wasserroth, Guanyu Lu +6
Super-resolution microscopy in the visible is an established powerful tool in several disciplines. In the infrared (IR) spectral range, however, no comparable schemes have been dem…
Layer-Resolved Absorption of Light in Arbitrarily Anisotropic Heterostructures
Nikolai Christian Passler, Mathieu Jeannin, Alexander Paarmann
We present a generalized formalism to describe the optical energy flow and spatially resolved absorption in arbitrarily anisotropic layered structures. The algorithm is capable of…
Surface Polariton-Like s-Polarized Waveguide Modes in Switchable Dielectric Thin-Films on Polar Crystals
Nikolai Christian Passler, Andreas Heßler, Matthias Wuttig +2
Surface phonon polaritons (SPhP) and surface plasmon polaritons (SPP), evanescent modes supported by media with negative permittivity, are a fundamental building block of nanophoto…
Surface phonon polariton resonance imaging using long-wave infrared-visible sum-frequency generation microscopy
Riko Kiessling, Yujin Tong, Alexander J. Giles +5
We experimentally demonstrate long-wave infrared-visible sum-frequency generation microscopy for imaging polaritonic resonances of infrared (IR) nanophotonic structures. This nonli…
Controlling Nanoscale Air-Gaps for Critically Coupled Surface Polaritons by Means of Non-Invasive White-Light Interferometry
Karsten Pufahl, Nikolai Christian Passler, Nicolai B. Grosse +3
We report an experimental method to control large-area air-gaps in the nanometer range for evanescent coupling of light to surface waves such as surface plasmon polaritons or surfa…
Strong Coupling of Epsilon-Near-Zero Phonon Polaritons in Polar Dielectric Heterostructures
Nikolai Christian Passler, Christopher R. Gubbin, Thomas Graeme Folland +7
We report the first observation of epsilon near zero (ENZ) phonon polaritons in an ultrathin AlN film fully hybridized with surface phonon polaritons (SPhP) supported by the adjace…
Second Harmonic Generation from Phononic Epsilon-Near-Zero Berreman Modes in Ultrathin Polar Crystal Films
Nikolai Christian Passler, Ilya Razdolski, D. Scott Katzer +4
Immense optical field enhancement was predicted to occur for the Berreman mode in ultrathin films at frequencies in the vicinity of epsilon near zero (ENZ). Here, we report the fir…
Generalized 4 4 Matrix Formalism for Light Propagation in Anisotropic Stratified Media: Study of Surface Phonon Polaritons in Polar Dielectric Heterostructures
Nikolai Christian Passler, Alexander Paarmann
We present a generalized 4 4 matrix formalism for the description of light propagation in birefringent stratified media. In contrast to previous work, our algorithm is cap…
Second Harmonic Generation from Critically Coupled Surface Phonon Polaritons
Nikolai Christian Passler, Ilya Razdolski, Sandy Gewinner +3
Mid-infrared nanophotonics can be realized using sub-diffractional light localization and field enhancement with surface phonon polaritons in polar dielectric materials. We experim…
Resonant enhancement of second harmonic generation in the mid-infrared using localized surface phonon polaritons in sub-diffractional nanostructures
Ilya Razdolski, Yiguo Chen, Alexander J. Giles +8
We report on strong enhancement of mid-infrared second harmonic generation (SHG) from SiC nanopillars due to the resonant excitation of localized surface phonon-polaritons within t…