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The authors use time-resolved scanning near-field optical microscopy to probe the ultrafast excitonic processes and their impact on waveguide operation in transition metal dichalcogenide crystals. They observe significant modulation of the complex index by monitoring waveguide modes on the fs time scale, and identify both coherent and incoherent manipulations of WSe₂ excitonic resonances.

The emergence of magnetically confined surface excitons enabled by antiferromagnetic spin correlations is reported, which leads to the confinement of excitons to the surface of layered antiferromagnet CrSBr.

Hyperbolic exciton polaritons (HEPs) are anisotropic light-matter excitations with promising applications, but their steady-state observation is challenging. Here, the authors report experimental evidence of HEPs in a van der Waals magnet, CrSBr, via cryogenic infrared near-field microscopy.

Experimental evidence for charge coupling to ferroelectric soft mode is scarce. Here, the authors find a photogenerated coherent phonon coupling to the electronic transition above the bandgap in the van der Waals ferroelectric semiconductor NbOI2.

The authors demonstrate a graphene/CrSBr heterostructure exhibiting anisotropic surface plasmon polariton (SPP) propagation in the mid-infrared and terahertz range. Charge transfer at the interface directs SPPs along the quasi-1D chains that compose each CrSBr layer, with propagation lengths varying by an order of magnitude between the two in-plane crystallographic axes.

Dirac magnetoexcitons with non-trivial nanoscale electrodynamics are formed from the excitation of Landau levels in charge-neutral graphene. Here, the Dirac magnetoexciton dispersion is directly imaged up to 7 T via a magneto cryogenic near-field microscope.

Excitons play an important role in the optical properties of 2D semiconductors, but their spatial characterization is usually constrained by the diffraction limit. Here, the authors report near-field optical spectroscopy of 2D transition metal dichalcogenides with 20 nm resolution, revealing their spatially dependent excitonic spectra and complex dielectric function.

Recent experiments have shown the formation of ferroelectric domains in twisted van der Waals bilayers. Here, the authors report near-field infrared nano-imaging and nano-photocurrent measurements to investigate ferroelectricity in minimally twisted WSe₂ by visualizing the plasmonic and photo-thermoelectric response of an adjacent graphene monolayer.

Researchers demonstrate efficient frequency conversion with rhombohedral MoS₂. A second-harmonic-generation coherence length of ~530 nm at 1,520 nm wavelength and giant nonlinear optical enhancement in waveguide geometries are reported.

s-SNOM is a powerful tool, but it is less sensitive to in-plane variations. Here the authors present a method to improve this with a metallic microdisk antenna, which they demonstrate by probing in-plane phonon responses.

The behaviour of Tungsten ditelluride (WTe2) in few-layer form is not yet fully characterized. Here the authors use a near-field terahertz microscopy technique to observe the electromagnetic responses of WTe2 flakes from one to several layers and to study their semimetallic/ semiconducting behavior.

What happens to topological materials when their electrons are strongly interacting is an open question. Shao and others demonstrate that ZrSiSe is a material that can address this as it has a topological band structure and non-trivial correlations.

Employing an oxidation-activated charge transfer strategy to oxidize transition-metal dichalcogenides into transition-metal oxides, the authors imprint plasmonic cavities with laterally abrupt doping profiles and nanoscale precision demonstrating plasmonic whispering-gallery resonators.