CsPbBr₃ and Cs₄PbBr₆ perovskite powders have been synthesized through a relatively simple low-temperature and low-cost method. Nanocrystalline films have also been deposited from solutions with four different molar compositions of binary salt precursors. Optical absorption, emission and excitation spectra have been performed in the UV-visible spectral range while X-ray diffraction (XRD) has been recorded to characterize the nanocrystal morphology for the different molar compositions. A preferential orientation of crystallites along the (024) crystalline plane has been observed as a function of the different deposition conditions in films growth. All the crystals show an absorption edge around 530 nm; Tauc plots of the absorption returned bandgaps ranging from 2.29 to 2.35 eV characteristic of CsPbBr₃ phase. We attribute the UV absorption band peaked at 324 nm to the fundamental band-to-band transition for Cs₄PbBr₆. It was observed that the samples with the most ordered Cs₄PbBr₆ crystals exhibited the most intense emission of light, with a bright green emission at 520 nm, which are however due to the luminescence of the inclusion of CsPbBr₃ nanoclusters into the Cs₄PbBr₆. The latter shows instead an intense UV emission. Differently, the pure CsPbBr₃ powder did not show any intense fluorescent emission. The excitation spectra of the green fluorescent emission in all samples closely resemble the CsPbBr₃ absorption with the peculiar dip around 324 nm as expected from density of state calculations reported in the literature.

Active wavelength‐scale optoelectronic components are widely used in photonic integrated circuitry, however coherent sources of light – namely optical lasers – remain the most challenging component to integrate. Semiconductor nanowire lasers (NWLs) represent a flexible class of light source where each nanowire (NW) is both gain material and cavity; however, strong coupling between these properties and the performance leads to inhomogeneity across the population. While this has been studied and optimized for individual material systems, no architecture‐wide insight is available. Here, nine NWL material systems are studied and compared using 55,516 NWLs to provide statistically robust insight into performance. These results demonstrate that, while it may be important to optimize internal quantum efficiency for certain materials, cavity effects are always critical. The study provides a roadmap to optimize the performance of NWLs made from any material: this can be achieved by ensuring a narrow spread of lengths and end‐facet reflectivities.

Nanowire‐based plasmonic lasers are now established as nano‐sources of coherent radiation, appearing as suitable candidates for integration into next‐generation nanophotonic circuitry. However, compared to their photonic counterparts, their relatively high losses and large lasing thresholds still pose a burdening constraint on their scalability. In this study, the lasing characteristics of zinc oxide (ZnO) nanowires on silver (Ag) and aluminum (Al) substrates, operating as optically‐pumped short‐wavelength plasmonic nanolasers, are systematically investigated in combination with the size‐dependent performance of the hybrid cavity. A nanomanipulation‐assisted single nanowire optical characterization combined with high‐throughput photoluminescence spectroscopy enabled the correlation of the lasing characteristics to the metal substrate and the nanowire diameter. The results evidence that the coupling between excitons and surface plasmons is closely tied to the relationship between substrate dispersive behavior and cavity diameter. Such coupling dictates the degree to which the lasing character, be it more plasmonic‐ or photonic‐like, can define the stimulated emission features and, as a result, the device performance.

Tailoring the emission of plasmonic nanowire-based lasers represents one of the major challenges in the field of nanoplasmonics, given the envisaged integration of such devices into on-chip all-optical circuits. In this study, we proposed a mode selection scheme based on distributed feedback, achieved via the external coupling of single zinc oxide nanowires to an aluminum grating, which enabled a quasi-single mode lasing action. The nano-manipulation of a single nanowire allowed for a reliable comparison of lasing emission characteristics in both planar (i.e., a nanowire on the metallic substrate) and on-grating configurations. We found that, by varying the orientation of the nanowire on the grating, only when the nano-cavity was perpendicular to the ridge direction, an additional peak emerged in the emission spectrum on the low-energy side of the gain envelope. As a consequence of the fulfillment of the Bragg condition, such a peak was attributed to a hybrid mode dominating the mode competition. Simulation results showed that the hybrid mode could be efficiently waveguided along the nanowire cavity and supported by localized plasmon polaritons building up at the raised features (“fences”) on top of metal grating ridges. Moreover, the hybrid mode was found to experience an extra reflectance of nearly 50% across the grating periods in addition to that provided by nanowire end facets.

The present work is concerned with the investigation of the nonlinear optical response of green emissive CsPbBr 3 nanocrystals, in the form of colloidal dispersions in toluene, synthesized via a room-temperature ligand-assisted supersaturation recrystallization (LASR) method. After carrying out a preliminary characterization via X-Ray Diffraction (XRD) and Absorption and Photoluminescence (PL) Spectroscopies, the optical nonlinearity of the asobtained colloids is probed by means of a single-beam Z-scan setup. Results show that the material in question, within the sensitivity of the experimental apparatus, exhibits a nonlinear refractive index n 2 that is the order of 10-15 cm 2 /W. Moreover, a three-photon absorption mechanism (3PA) is postulated, according to the fitting of the recorded Z-scan traces and the fundamental absorption threshold, which turns out to be off resonance with twice the energy of the laser radiation. A figure of merit is, then, calculated as an indicator of the quality of the CsPbBr 3 nanocrystals as a candidate material for photonic devices, for instance, Kerr-like electro-optic modulators (EOMs).