Manipulation of resonant dielectric nanostructures is of paramount importance for next-generation photonic devices. Traditionally, researchers use two-dimensional or phase-change materials for this purpose. However, the former leads to small efficiency, while the latter lacks continuous changes. Here, we provide an alternative approach through laser-induced modification. Specifically, via a laser ablation process we synthesized molybdenum disulfide (MoS₂) nanoparticles (NPs), the composition of which we then controlled through laser fragmentation. It causes a transformation of MoS₂ into its oxide MoO_3−x, which, in turn, results in pronounced modification of the optical response, owing to a large difference between their optical constants. In addition, laser-fragmented NPs have a several times larger photothermal response, compared to the original MoS₂ and classical silicon NPs. Thus, our MoS₂-based laser-tunable NPs open up a new perspective for resonant nanophotonics, in particular, photothermal therapy.

Resonant optical responses of anisotropic molybdenum disulfide (${\mathrm{MoS}}_2$) nanoparticles (NPs) and their two-dimensional arrays (metasurfaces) are investigated. The nanoparticles in the form of disks with holes and with ${\mathrm{MoS}}_2$ layers oriented perpendicular to the disk's basis (in-plane material anisotropy) are considered. Using numerical calculations with analytical multipole analysis, we show that the material anisotropy of NPs provides an additional degree of freedom for manipulation of their resonant magnetic and electric dipole responses and affect the effective dipole polarizabilities. Based on this possibility and applying a special tuning procedure, we construct the ${\mathrm{MoS}}_2$ metasurfaces supporting the quasitrapped mode (QTM) resonance around the telecom wavelength of 1550 nm with high quality factor and high sensitivity to the environment. It is shown that regardless of extremely weak absorption of the single nanoparticles, the excitation of the QTM leads to effective narrowband absorption in the telecom wavelength range depending on the polarization direction of normally incident waves. It is demonstrated that a metasurface, composed of the ${\mathrm{MoS}}_2$ disks with the in-plane material anisotropy, has the properties of a continuous birefringent medium. Due to these properties, a normally incident linearly polarized wave can be transformed into transmitted and reflected waves with changed polarizations.

New practical ways to reach the lasing effect in symmetrical metasurfaces have been developed and theoretically demonstrated. Our approach is based on excitation of the resonance of an octupole quasi-trapped mode (OQTM) in heterostructured symmetrical metasurfaces composed of monolithic disk-shaped van der Waals meta-atoms featured by thin photoluminescent layers and placed on a substrate. We revealed that the coincidence of the photoluminescence spectrum maximum of these layers with the wavelength of high-quality OQTM resonance leads to the lasing effect. Based on the solution of laser rate equations and direct full-wave simulation, it was shown that lasing is normally oriented to the metasurface plane and occurs from the entire area of metasurface consisting of MoS₂/hBN/MoTe₂ disks with line width of generated emission of only about 1.4 nm near the wavelength 1140 nm. This opens up new practical possibilities for creating surface emitting laser devices in subwavelength material systems.

Nonlinear plasmonic effects in perspective 2D materials containing low-dimensional quantum emitters can be a basis of a novel technological platform for the fabrication of fast all-plasmonic triggers, transistors, and sensors. This article considers the conditions for achieving a strong coupling between the surface plasmon–polariton (SPP) and quantum emitter taking into account the modification of local density of optical states in graphene waveguide. In the condition of strong coupling, nonlinear interaction between two SPP modes propagating along the graphene waveguide integrated with a stub nanoresonator loaded with core–shell semiconductor nanowires (NWs) was investigated. Using the 2D full-wave electromagnetic simulation, we studied the different transmittance regimes of the stub with NW for both the strong pump SPP and weak signal SPP tuned to interband and intraband transition in NW, respectively. We solved the practical problem of parameters optimization of graphene waveguide and semiconductor nanostructures and found such a regime of NW–SPP interaction that corresponds to the destructive interference with the signal SPP transmittance through the stub less than $7\%$ in the case for pump SPP to be turned off. In contrast, the turning on the pump SPP leads to a transition to constructive interference in the stub and enhancement of signal SPP transmittance to $93\%$ . In our model, the effect of plasmonic switching occurs with a rate of $50\mathrm{GHz}$ at wavelength $8\mathsf{\mu }\mathrm{m}$ for signal SPP localized inside $20\mathrm{nm}$ graphene stub loaded with core–shell InAs/ZnS NW.