Search

The use of photons to directly or indirectly drive chemical reactions has revolutionized the field of nanomaterial synthesis resulting in appearance of new sustainable laser chemistry methods for manufacturing of micro‐ and nanostructures. The incident laser radiation triggers a complex interplay between the chemical and physical processes at the interface between the solid surface and the liquid or gas environment. In such a multi‐parameter system, the precise control over the resulting nanostructures is not possible without deep understanding of both environment‐affected chemical and physical processes. The present review intends to provide detailed systematization of these processes surveying both well‐established and emerging laser technologies for production of advanced nanostructures and nanomaterials. Both gases and liquids are considered as potential reacting environments affecting the fabrication process, while subtractive and additive manufacturing methods are analyzed. Finally, the prospects and emerging applications of such technologies are discussed. [ABSTRACT FROM AUTHOR]

Halide perovskites have become a versatile platform not only for optoelectronic devices but also for modern optics and nanophotonics. Perovskite nano‐ and micro‐particles, metasurfaces, and photonic crystals demonstrate their applicability for directional enhanced photo‐ and electro‐luminescence, lasing, as well as for improving the performance of optoelectronic devices. However, ionic nature makes perovskites water soluble, while their high sensitivity to diverse chemicals complicates their patterning toward the formation of functional, high‐quality nanostructures. Here, recent progress on emerging laser technologies for processing and nanopatterning of halide perovskites, as well as their applications in designing advanced light‐emitting systems and controlling light at the nanoscale is overviewed. Special emphasis is made on the processes underlying the interaction of laser radiation with perovskites to disclose new avenues for their surface and volume modification with ultra‐high precision and a high degree of material's property control. [ABSTRACT FROM AUTHOR]

Upon systematic studies of femtosecond‐laser processing of monocrystalline Si in oxidation‐preventing methanol, it is shown that the electromagnetic processes dominating at initial steps of the progressive morphology evolution define the onset of the hydrodynamic processes and morphology upon subsequent multi‐pulse exposure. Under promoted exposure quasi‐regular subwavelength laser‐induced periodic surface structures (LIPSSs) are justified to evolve through the template‐assisted development of the Rayleigh‐Plateau hydrodynamic instability in the molten ridges forming quasi‐regular patterns with a supra‐wavelength periodicity and preferential alignment along polarization direction of the incident light. Subsequent exposure promotes fusion‐assisted morphology rearrangement resulting in a spiky surface with random orientation, yet constant inter‐structure distance correlated with initial LIPSS periodicity. Along with the insight onto the physical picture driving the morphology evolution and supra‐wavelength nanostructure formation, this experiments also demonstrated that resulting quasi‐regular and random spiky morphology can be tailored by the intensity/polarization distribution of incident laser beam allowing on‐demand surface nanotexturing with diverse hierarchical surface morphologies exhibiting reduced reflectivity at visible and shortwave‐IR wavelengths. Finally, the practical attractiveness of the suggested approach for improving near‐IR photoresponse and expanding operation spectral range of vertical p‐n junction Si photodetector operating under room temperature and zero‐bias conditions via single‐step annealing‐free nanopatterning is highlighted. [ABSTRACT FROM AUTHOR]

In order to advance the development of quantum emitter‐based devices, it is essential to enhance light‐matter interactions through coupling between semiconductor quantum dots with high quality factor resonators. Here, efficient tuning of the emission properties of HgTe quantum dots in the infrared spectral region is demonstrated by coupling them to a plasmonic metasurface that supports bound states in the continuum. The plasmonic metasurface, composed of an array of gold nanobumps, is fabricated using single‐step direct laser printing, opening up new opportunities for creating exclusive 3D plasmonic nanostructures and advanced photonic devices in the infrared region. A 12‐fold enhancement of the photoluminescence in the 900–1700 nm range is observed under optimal coupling conditions. By tuning the geometry of the plasmonic arrays, controllable shaping of the emission spectra is achieved, selectively enhancing specific wavelength ranges across the emission spectrum. The observed enhancement and shaping of the emission are attributed to the Purcell effect, as corroborated by systematic measurements of radiative lifetimes and optical simulations based on the numerical solution of Maxwell's equations. Moreover, coupling of the HgTe photoluminescence to high quality factor modes of the metasurface improves emission directivity, concentrating output within an ≈20° angle. [ABSTRACT FROM AUTHOR]

Halide perovskite lasers based on CsPbBr3 micro‐ and nanoscale crystals have demonstrated fascinating performance owing to their low‐threshold lasing at room temperature and cost‐effective fabrication. However, chemically synthesized thin films of CsPbBr3 usually have rough polycrystalline morphology along with a large amount of crystal lattice defects and, thus, are mostly utilized for the engineering of light‐emitting devices. This obstacle prevents their usage in many photonic applications. Here, a protocol to deposit large‐grain and smooth CsPbBr3 thin films is developed. Their high quality and large scale allow to demonstrate a maximum optical gain up to 12 900 cm−1 in the spectral range of 530–540 nm, which is a record‐high value among all previously reported halide perovskites and bulk semiconductors (e.g., GaAs, GaN, etc.) at room temperature. Moreover, femtosecond laser ablation technique is employed to create high‐quality microdisc lasers on glass from these films to obtain excellent lasing characteristics. The revealed critical roles of thickness and grain size for the CsPbBr3 films with extremely high optical gain pave the way for development of low‐threshold lasers or ultimately small nanolasers, as well as to apply them for polaritonic logical elements and integrated photonic chips. [ABSTRACT FROM AUTHOR]

Gold@mesoporous silica nanosheet (Au@MSNS) catalyst was synthesized by one‐pot reduction of HAuCl4 with formaldehyde. Subsequent SiO2 recoating procedure was shown to reduce the average size of the loading Au nanoparticles, resulting in significantly improved catalytic activity of the modified Au@MSNSs against reduction of 4‐nitrophenol. Moreover, this procedure improves mechanical properties and reusability of the catalyst demonstrating superior turnover frequency of 91.954 × 10−3 mol g−1 h−1 in cyclic reaction. [ABSTRACT FROM AUTHOR]

Ultrashort laser pulses deliver electromagnetic energy to matter causing its localized heating that can be used for both material removal via ablation/evaporation and driving interface chemical reactions. Here, it is shown that both mentioned processes can be simultaneously combined within straightforward laser nanotexturing of Si wafer in a functionalizing solution to produce a practically relevant metal–semiconductor surface nano‐morphology. Such unique hybrid morphology represents deep‐subwavelength Si laser‐induced periodic surface structures (LIPSSs) with an extremely short period down to 70 nm and high‐aspect‐ratio nano‐trenches loaded with controllable amount of plasmonic nanoparticles formed via laser‐induced decomposition of the precursor noble‐metal salts. Moreover, heat localization driving reduction process is utilized to produce surface morphology locally decorated with dissimilar plasmon‐active nanoparticles. Light‐absorbing deep‐subwavelength Si LIPSSs loaded with controllable amount of noble‐metal nanoparticles represent an attractive architecture for plasmon‐related applications such as optical nanosensing where efficient coupling of the propagating optical waves to highly localized electromagnetic "hot spots" is a mandatory requirement. To support this statement, applicability of such hybrid morphology for fluorescence‐based detection of nanomolar concentrations of mercury cations in solution is demonstrated. [ABSTRACT FROM AUTHOR]

Abstract: Over more than 40 years since its discovery, surface‐enhanced Raman scattering/spectroscopy (SERS) has attracted substantial attention as a tool for fundamental research in surface science and for potential analytical sensing applications. This review aims to concisely summarize the essential principles of both the physical and chemical processes underlying Raman signal enhancement, as well as elements of the broader field of plasmonics that are most relevant to SERS. In order to make sense of the overwhelming variety of SERS platforms that are reported, the fabrication, properties, and operational principles of enhancing substrates are given particular attention here in the context of specific application requirements. While the high spatial precision of lithographic techniques has helped to improve the understanding of plasmonic platforms, their prohibitive cost has encouraged the exploration of more facile fabrication methods for more widespread adoption of SERS. Selected examples are introduced to illustrate common themes that recur in fundamental studies, analytical applications, and efforts to produce stable, affordable, and robust SERS sensing platforms. [ABSTRACT FROM AUTHOR]

Interaction of light pulses of various durations and intensities with nanoscale photonic structures plays an important role in many applications of nanophotonics for high-density data storage, ultra-fast data processing, surface coloring and sensing. A design of optically tunable and reconfigurable structures made from different materials is based on many important physical effects and advances in material science, and it employs the resonant character of light interaction with nanostructures and strong field confinement at the nanoscale. Here we review the recent progress in physics of tunable and reconfigurable nanophotonic structures of different types. We start from low laser intensities that produce weak reversible changes in nanostructures, and then move to the discussion of non-reversible changes in photonic structures. We focus on three platforms based on metallic, dielectric and hybrid resonant photonic structures such as nanoantennas, nanoparticle oligomers and nanostructured metasurfaces. Main challenges and key advantages of each of the approaches focusing on applications in advanced photonic technologies are also discussed. [ABSTRACT FROM AUTHOR]

Gold@mesoporous silica nanosheet (Au@MSNS) catalyst was synthesized by one‐pot reduction of HAuCl4 with formaldehyde. Subsequent SiO2 recoating procedure was shown to reduce the average size of the loading Au nanoparticles, resulting in significantly improved catalytic activity of the modified Au@MSNSs against reduction of 4‐nitrophenol. Moreover, this procedure improves mechanical properties and reusability of the catalyst demonstrating superior turnover frequency of 91.954 × 10−3 mol g−1 h−1 in cyclic reaction. [ABSTRACT FROM AUTHOR]