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Developing intense, coherent and ultra-fast light sources with nanoscale dimensions is a crucial issue for many applications in nanophotonics. To date, plasmonic nanolasers represent one of the most promising nanophotonic devices capable of this remarkable feature. In the present work we report on the emission properties of two-dimensional Au hexagonal nanodome arrays, fabricated by nanosphere lithography, coupled with a dye liquid solution used as the gain medium. Low-threshold stimulated emission at room temperature is demonstrated by spectral and angle-resolved photoluminescence measurements performed as a function of the pump fluence. The emission arises with narrow angular divergence in off-normal direction, out of high-symmetry points of the plasmonic lattice. The polarization properties of the stimulated emission are investigated, revealing a strong linear polarization character controlled by the polarization orientation of the pumping beam, while the first-order temporal coherence properties are measured by using a tilted-mirrors Michelson interferometer. Finally, by comparing the results obtained for the plasmonic Au nanodomes arrays with those of purely dielectric nanoarrays, the role of the plasmonic modes and the photonic lattice modes in the emission process is highlighted. [ABSTRACT FROM AUTHOR]

Halide perovskite quantum dots (PeQDs) are characterized by a size-dependent emission spectrum and an intrinsic lack of preferential emission directions. Thus, new means for shaping the typical Lambertian angular profile of thin layers embedding such PeQDs are highly desirable for several photonics applications, including solid-state lighting devices. Here, we show that the photoluminescence pattern of PeQDs can be changed drastically by weakly coupling them to plasmonic lattices at emission wavelengths. The coupling to extended collective optical modes supported by the lattices converts the ensemble of incoherent randomly oriented emitters into a spatially coherent source of polarized light with a wavelength-dependent intensity enhancement of about one order of magnitude. The dispersive character of the narrow collective optical modes is key to achieving intensity enhancement of the entire perovskite emission spectrum, especially its tails, together with beaming into definite directions. Further, we optimize the thickness of the perovskite layer to realize simultaneous shaping of its emission by plasmonic lattices of different symmetries. This flexibility paves the way to designing advanced photonic architectures based on PeQDs for solid-state lighting applications requiring programmable emission patterns. [ABSTRACT FROM AUTHOR]

The increased interest in white solid-state lighting devices addresses the urgent challenge to develop semiconductors with broad band emission. In recent years, low dimensional hybrid organic/inorganic lead perovskites have shown great potential as single white-light emitters. Herein, we show that it is possible to control the chirality of lead bromide perovskites by incorporating enantiopure (R or S) or racemic (RS) β-methylphenethylammonium. The incorporation of such cations allows us to control the chirality of the resulting materials and yields the first examples of 2D chiral perovskites that emit white light. Furthermore, we demonstrate that these materials exhibit second harmonic generation. Our results demonstrate the potential of this kind of materials for chiroptical applications and non-linear optics. [ABSTRACT FROM AUTHOR]