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Semiconductor nanocrystals (NCs) can function as efficient gain materials with chemical versatility because of their surface ligands. Because the properties of NCs in solution are sensitive to ligand–environment interactions, local chemical changes can result in changes in the optical response. However, amplification of the optical response is technically challenging because of colloidal instability at NC concentrations needed for sufficient gain to overcome losses. This paper demonstrates liquid lasing from plasmonic lattice cavities integrated with ligand-engineered CdZnS/ZnS NCs dispersed in toluene and water. By taking advantage of calcium ion-induced aggregation of NCs in aqueous solutions, we show how lasing threshold can be used as a transduction signal for ion detection. Our work highlights how NC solutions and plasmonic lattices with open cavity architectures can serve as a biosensing platform for lab-on-chip devices. 

The generation of exciton–polaritons through strong light–matter interactions represents an emerging platform for exploring quantum phenomena. A significant challenge in colloidal nanocrystal-based polaritonic systems is the ability to operate at room temperature with high fidelity. Here, we demonstrate the generation of room-temperature exciton–polaritons through the coupling of CdSe nanoplatelets (NPLs) with a Fabry–Pérot optical cavity, leading to a Rabi splitting of 74.6 meV. Quantum–classical calculations accurately predict the complex dynamics between the many dark state excitons and the optically allowed polariton states, including the experimentally observed lower polariton photoluminescence emission, and the concentration of photoluminescence intensities at higher in-plane momenta as the cavity becomes more negatively detuned. The Rabi splitting measured at 5 K is similar to that at 300 K, validating the feasibility of the temperature-independent operation of this polaritonic system. Overall, these results show that CdSe NPLs are an excellent material to facilitate the development of room-temperature quantum technologies. 

This paper describes how two-dimensional plasmonic nanoparticle latticescovered with microscale arrays of dielectric patches can show superlattice surface latticeresonances (SLRs). These optical resonances originate from multiscale diffractive coupling thatcan be controlled by the periodicity and size of the patterned dielectrics. The features in theoptical dispersion diagram are similar to those of index-matched microscale arrays of metalnanoparticle lattices, having the same lateral dimensions as the dielectric patches. With anincrease in nanoparticle size, superlattice SLRs can also support quadrupole excitations withdistinct dispersion diagrams. The tunable optical band structure enabled by patterned dielectricson plasmonic nanoparticle arrays offers prospects for enhanced nonlinear optics, nanoscalelasing, and engineered parity-time symmetries.