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Bio‐inspired and biodegradable quantum optics scenarios constitute a pathway toward environmentally friendly front‐end technologies. Such an inspiring perspective necessitates the replacement of classic gain materials with a biological counterpart like photoluminescent bacteria. It is easy to imagine that, in this case, a planar and cell‐viable substitute of classic bulk solid‐states resonators can be highly beneficial. In this paper a micro‐ and nano‐photonic structuration of both a standard and a functionalized version of a typical bacterial growth medium (Luria‐Bertani Agar – LBA) is successfully realized. Three structures belonging to the categories of photonic crystals are replicated, such as quasi‐crystals and meta‐surfaces, demonstrating how the proposed media can be used as templates for high‐end photonic applications. The optical quality of the replicated structures is confirmed by far‐field diffraction measurements. The structured growth media allow for a broad control of the surface wettability by accessing a so‐called Wenzel state, in which the original hydrophilicity of a material is increased due to the photonic structuration. Finally, the suitability of the nano‐structured LBA as a plasmonic platform is evidenced. The proposed micro‐and nano‐structured photonic growth media constitute the first, fundamental step toward quantum optical frameworks from biological media. [ABSTRACT FROM AUTHOR]

All‐inorganic metal halide perovskites are highly attractive materials for optoelectronics and are typically implemented as thin films, nanocrystals, and single crystals with macroscopic and millimeter‐size dimensions. Single crystals with regular shapes in the micrometer range are less explored and present an interesting alternative when a well‐defined and spatially localized response is desired. Here, CsPbBr3 microcrystals are fabricated by simple and fast drop‐casting of a precursor solution on several substrates that for the growth process are heated to temperatures in the range from 80 to 150 °C. The microcrystals have a cubic shape and feature a pyramidal cavity on their top surface that forms due to faster growth at the edges once the growing crystal is attached to the substrate. Distinct heterogeneity in the photoluminescence (PL) and conductivity of the different facets are measured by µ‐PL and conductive atomic force microscopy experiments. Toward device applications, the authors contact single microcrystals on conductive substrates mechanically with a micromanipulator tip. They observe diode‐like current–voltage curves and good photodetector functionality, obtaining a high responsivity of 150–300 A W−1 in the blue–green spectral region under forward bias, and a sharp detection band centered around 540 nm with peak responsivity close to 0.7 A W−1 under reverse bias. [ABSTRACT FROM AUTHOR]

Solid‐state nanopore gating inspired by biological ion channels is gaining increasing traction due to a large range of applications in biosensing and drug delivery. Integration of stimuli‐responsive molecules such as poly(N‐isopropylacrylamide) (PNIPAM) inside nanopores can enable temperature‐dependent gating, which so far has only been demonstrated using external heaters. In this work, plasmonic resonators are combined inside the nanopore architecture with PNIPAM to enable optical gating of individual or multiple nanopores with micrometer resolution and a switching speed of a few milliseconds by thermo‐plasmonics effects. A temperature change of 40 kelvin per millisecond is achieved and demonstrates the efficacy of this method using nanopore ionic conductivity measurements that enable selective activation of individual nanopores in an array. Moreover, the selective gating of specific nanopores in an array can set distinct ionic conductance levels: low, medium, and high (i.e., “0,” “1,” and “2”), which can be exploited for logical gating with optical signal control. Such selective optical gating in nanopore arrays marks a breakthrough in nanofluidics, as it paves the way toward smart devices that offer multifunctional applications including biosensing, targeted drug delivery, and fluidic mixing. [ABSTRACT FROM AUTHOR]

Colloidal core/shell nanocrystals are key materials for optoelectronics, enabling control over essential properties via precise engineering of the shape, thickness, and crystal structure of their shell. Here, the growth protocol for CdS branched nanocrystals is applied on CdSe nanoplatelet seeds and bone‐shaped heterostructures are obtained with a highly anisotropic shell. Surprisingly, the nanoplatelets withstand the high growth temperature of 350 °C and structures with a CdSe nanoplatelet core that is overcoated by a shell of cubic CdS are obtained, on top of which tetrahedral CdS structures with hexagonal lattice are formed. These complex core/shell nanocrystals show a band‐edge emission around 657 nm with a photoluminescence quantum yield of ≈42% in solution, which is also retained in thin films. Interestingly, the nanocrystals manifest simultaneous red and green emission and the relatively long wavelength of the green emission indicates charge recombination at the cubic/hexagonal interface of the CdS shell. The nanocrystal films show amplified spontaneous emission, random lasing, and distributed feedback lasing when the material is deposited on suitable gratings. This work stimulates the design and fabrication of more exotic core/shell heterostructures where charge carrier delocalization, dipole moment, and other optical and electrical properties can be engineered. [ABSTRACT FROM AUTHOR]

Directing and polarizing the emission of a fluorophore is of fundamental importance in the perspective of novel photonic sources based on emerging nanoemitter technologies. These two tasks are usually accomplished by a sophisticated and demanding structuring of the optical environment in which the emitter is immersed, or by nontrivial chemical engineering of its geometry and/or band structure. Here, the wavelength and polarization selective spontaneous emission from a dye‐embedded in a metal/insulator/metal (d‐MIM) nanocavity is demonstrated. A push–pull chromophore with large Stokes shift is embedded in a MIM cavity whose resonances are tuned with the spectral emission band of the chromophore. Angular and polarization resolved spectroscopy experiments reveal that the radiated field is reshaped according to the angular dispersion of the nanocavity, and that its spectrum manifests two bands with different polarization corresponding to the p‐ and s‐polarized resonances of the cavity. The d‐MIM cavities are a highly versatile system for polarization and wavelength division multiplexing applications at the nanoscale, as well as for near‐field focused emission and nanolenses. [ABSTRACT FROM AUTHOR]