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Nonlinear Luttinger liquid plasmons in semiconducting single-walled carbon nanotubes
摘要： Interacting electrons confined in one dimension are generally described by the Luttinger liquid formalism, where the low-energy electronic dispersion is assumed to be linear and the resulting plasmonic excitations are non-interacting. Instead, a Luttinger liquid in one-dimensional materials with nonlinear electronic bands is expected to show strong plasmon–plasmon interactions, but an experimental demonstration of this behaviour has been lacking. Here, we combine infrared nano-imaging and electronic transport to investigate the behaviour of plasmonic excitations in semiconducting single-walled carbon nanotubes with carrier density controlled by electrostatic gating. We show that both the propagation velocity and the dynamic damping of plasmons can be tuned continuously, which is well captured by the nonlinear Luttinger liquid theory. These results contrast with the gate-independent plasmons observed in metallic nanotubes, as expected for a linear Luttinger liquid. Our findings provide an experimental demonstration of one-dimensional electron dynamics beyond the conventional linear Luttinger liquid paradigm and are important for understanding excited-state properties in one dimension.
关键词： single-walled carbon nanotubes,Nonlinear Luttinger liquid,infrared nano-imaging,plasmons,electronic transport
更新于2025-09-23 15:21:01
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Metallic Carbon Nanotube Nanocavities as Ultra-compact and Low-loss Fabry-Perot Plasmonic Resonators
摘要： Plasmonic resonators enable deep subwavelength manipulation of light matter interactions and have been intensively studied both in fundamental physics as well as for potential technological applications. While various metallic nanostructures have been proposed as plasmonic resonators, their performances are rather limited at mid- and far-infrared wavelengths. Recently, highly-confined and low-loss Luttinger liquid plasmons in metallic single walled carbon nanotubes (SWNTs) have been observed at infrared wavelengths. Here, we tailor metallic SWNTs into ultraclean nanocavities by advanced scanning probe lithography and investigate plasmon modes in these individual nanocavities by infrared nano-imaging. The dependence of mode evolutions on cavity length and excitation wavelength can be captured by a Fabry-Perot resonator model of a plasmon nanowaveguide terminated by highly reflective ends. Plasmonic resonators based on SWNT nanocavities approach the ultimate plasmon confinement limit and open the door to the strong light-matter coupling regime, which may enable various nanophotonic applications.
关键词： Plasmonic nanocavity,Carbon nanotubes,Nanophotonics,Infrared nano-imaging
更新于2025-09-19 17:13:59
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Grayscale Nanopatterning of Phase-Change Materials for Subwavelength-Scaled, Inherently Planar, Nonvolatile, and Reconfigurable Optical Devices
摘要： The integration of phase-change materials into the design of optical metasurfaces already enables dynamically switchable, tunable, and reconfigurable optical devices. Their functionality is based on fast and repeatable switching between two stable states - amorphous and crystalline - which is typically accompanied by drastic changes of the electrical and optical properties and can be accomplished by external stimuli. In this study, we demonstrate that focused ion beam irradiation can be used to locally tailor the amount of disorder in phase-change materials in highly confined regions, which was examined both in the visible and mid infrared by using optical nano-imaging techniques such as photo-induced force microscopy and scattering type scanning near-field optical microscopy. Our approach enables grayscale patterning at the nanoscale circumventing the diffraction limit of common laser light sources and thus literally adds a further degree of freedom for the design of optical devices that are subwavelength-scaled, inherently planar, nonvolatile, and reconfigurable.
关键词： focused ion irradiation,grayscale,tailoring disorder,nanopatterning,phase-change materials,nano-imaging
更新于2025-09-19 17:13:59
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Heterogeneous Cationa??Lattice Interaction and Dynamics in Triple-Cation Perovskites Revealed by Infrared Vibrational Nanoscopy
摘要： Hybrid organic-inorganic perovskites exhibit extraordinary photovoltaic performance. This is believed to arise from almost liquid-like low-energy interactions among lattice ions and charge carriers. While spatial variations have recently been identified over multiple length scales in the optoelectronic responses, the relationship of the heterogeneity and the soft cation-lattice interactions has remained elusive. Here, we apply multivariate infrared vibrational nano-imaging to a formamidinium (FA)-methylammonium (MA)-cesium triple cation perovskite. By using the FA vibrational resonance as a probe of its local chemical environment, through spatial variation and correlation in composition, strength of cation-lattice coupling and its associated few-ps vibrational dynamics, we reveal how a varying local reaction field is correlated with the cation-lattice coupling. We attribute the associated heterogeneous lattice contraction to a non-uniform distribution of cesium cations. The observed varying elasticity of the lattice leads to disordered charge-phonon coupling and polaron formation, the control of which is central to improving perovskite photovoltaics.
关键词： charge-phonon coupling,infrared vibrational nano-imaging,Hybrid organic-inorganic perovskites,lattice contraction,photovoltaic performance,cation-lattice coupling,polaron formation,vibrational dynamics
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE/MTT-S International Microwave Symposium - IMS 2019 - Boston, MA, USA (2019.6.2-2019.6.7)] 2019 IEEE MTT-S International Microwave Symposium (IMS) - Borrowing from Microwave Holography a Technique for Broad-band Nano Imaging at Infrared Wavelengths
摘要： Scanning Probe Microscopy (SPM) for Nano imaging includes different techniques, ranging from Atomic Force Microscopy (AFM) and Scanning Near-Field Optical Microscopy (able to acquire images beyond diffraction limit), up to Scanning Microwave Microscopy developed to achieve imaging and characterization of a sample at Microwaves. In the present work we describe a technique which implements the concept of “Synthetic Reference Wave”, borrowed from Microwave Holography and already introduced in Synthetic Aperture Radars (SAR), to perform Nano scale quantitative imaging at infrared wavelengths. Although this approach was already combined in the past with AFM, in the following paper we proposed a different implementation, potentially suitable for wide-band imaging at Nano scale.
关键词： Nano Imaging,Scanning Probe Microscopy,Microwave Holography
更新于2025-09-16 10:30:52
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Photonic crystal for graphene plasmons
摘要： Photonic crystals are commonly implemented in media with periodically varying optical properties. Photonic crystals enable exquisite control of light propagation in integrated optical circuits, and also emulate advanced physical concepts. However, common photonic crystals are un?t for in-operando on/off controls. We overcome this limitation and demonstrate a broadly tunable two-dimensional photonic crystal for surface plasmon polaritons. Our platform consists of a continuous graphene monolayer integrated in a back-gated platform with nano-structured gate insulators. Infrared nano-imaging reveals the formation of a photonic bandgap and strong modulation of the local plasmonic density of states that can be turned on/off or gradually tuned by the applied gate voltage. We also implement an arti?cial domain wall which supports highly con?ned one-dimensional plasmonic modes. Our electrostatically-tunable photonic crystals are derived from standard metal oxide semiconductor ?eld effect transistor technology and pave a way for practical on-chip light manipulation.
关键词： graphene plasmons,tunable,infrared nano-imaging,Photonic crystal,surface plasmon polaritons
更新于2025-09-11 14:15:04