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Photothermal conversion of energy in plasmonic nanostructures brought a new fascinating field of plasmon‐induced optofluidics to life. Notably, the heat generation by plasmonic nanostructures and consequent fluid convection recently attracted wide attention; however, the possibility of controlling and manipulating liquid surfaces has been sparsely investigated. The plasmon heating and convective fluid flow lead to the emergence of the surface tension gradient on a free liquid surface interface with air, resulting in the Marangoni effect‐driven fluid flow observed as water deformation. Here, nanoscale asymmetric fluid deformation anchored on the chiral plasmon‐induced optofluidic effect is reported on. To understand the fluid dynamics of surface deformation, a theoretical model is developed. The results demonstrate that deformation at different depths can be obtained by adjusting structural parameters or incident light intensity. The fundamental understanding of light‐induced asymmetric deformation will contribute to expanding chirality‐related discipline and open new avenues for controlling fluid flow at the micro‐ or nano‐scale. The proposed method can encourage the research and applications of optofluidics, including integrated fluidic devices, biochemistry, and clinical biology. Moreover, the use of the asymmetric fluid deformation on thermal dewetting of thin films of polymer solutions can be employed for the fabrication of functional and nanopatterned metal/polymer metasurfaces. [ABSTRACT FROM AUTHOR]

Can chiral light induce chiral shapes in nanocrystals in a diluted solution? So far, it has been unclear whether it could be and, if such, under which conditions it may occur. By using realistic models of plasmonic nanocrystals, this work shows that the imprinting of 3D chirality on nanocrystals in solution by circularly polarized light (CPL) is possible. Such 3D‐chiral patterns originate from the electromagnetic retardation effect. This work investigates the formation of chiral spatial distributions of the near fields and hot electrons produced by CPL in both substrate and solution settings. Anisotropic nanocrystals with sharp edges and tips are preferable for inducing 2D and 3D chirality because of the formation of chiral hot‐spot patterns on them. The 2D g‐factors are always much higher than the 3D ones. In addition, 3D‐chiral imprinting on spherical nanocrystals is impossible. With linearly polarized light (LPL), one can create chiral nanocrystals on a substrate, not in a solution. This study provides the principles for emerging technologies to create chiral nanostructures using CPL and LPL illuminations. [ABSTRACT FROM AUTHOR]

Chiral artificial nanosystems constructed from inorganic nanoparticles brought about a paradigm shift in chiral sensing, enantioselective catalysis, chiral polarization engineering, and chiral emission due to their strong light–matter interaction and their precisely engineered properties. Especially bottom‐up approaches hold great potential for the inexpensive, scalable production of plasmonic, excitonic, and upconversion chiral materials. This perspective first reviews the state‐of‐the‐art fabrication schemes: chiral molecule‐induced chirality, chiral nanoparticle growth, and assembly of chiral superstructures from achiral building blocks. Next, the emerging field of dynamically tunable chiroptical materials, promising for adaptive thin‐film optics, display technologies, and information encoding, is explored. Here, the strength of chiral assemblies based on their rich tuning mechanisms and their ability for geometrical reconfiguration is highlighted. Finally, promising future directions and opportunities in the field of active chiroptical materials are discussed. [ABSTRACT FROM AUTHOR]

Surface lattice plasmon resonances (SLPR) in periodic arrays of metal nanostructures can feature a narrow spectral linewidth in case of the spectral overlap between the localized plasmons and Rayleigh anomalies. However, because of strong angular dispersion in experimental realizations, the excitation of SLPR requires collimated light, which has high spatial coherence. Here, excellent quality (Q)‐factor preservation in 1D all‐metallic nanograting metasurfaces due to the unique angular dispersion is reported. A high Q‐factor around 400 is obtained even when poor collimation, a numerical aperture (NA) objective with NA = 0.4, is employed for focusing the excitation light. With the advantages of highly focused excitation and high Q‐factor of the SLPR, a strong enhancement of second harmonic generation is realized from the proposed metasurface integrated with a few‐layers of GaSe flake. The results demonstrate that a 1D all‐metallic nanograting metasurface can overcome the demand for collimated light for the SLP resonances and manipulate focused light beams. The avenue of research proposed in this paper can open the door for the use of plasmonic metamaterials with SLPRs in many practical applications involving poorly coherent light sources, like the optoelectronic devices utilizing solar and daylight illuminations. [ABSTRACT FROM AUTHOR]

The capability of plasmonic metasurfaces (PMs) under illumination to generate heat and induce fluid convection is a promising building approach for optofluidic applications. However, the low quality (Q)‐factor in PMs introduced into optofluidic applications remains a challenging problem. In this paper, a PM optofluidic platform based on surface lattice resonance (SLR) with a high Q‐factor is proposed. Numerical results demonstrate that SLR‐based metasurfaces can manipulate the convective flow of fluid at the nanoscale, with the Q‐factor approaching 138. Moreover, compared to the localized surface plasmon resonance‐based metasurface, the SLR‐based metasurfaces exhibit improved absorption, temperature rise, and flow velocity performance. In particular, the absorption coefficient at the SLR peak in an adequately designed PM can be close to unity. This study reveals that SLR is an efficient and alternative method to manipulate the fluid flow, and paves the way to flexible wavelength‐scale devices for optofluidic applications. [ABSTRACT FROM AUTHOR]

Although the concept of chirality has its origin in chemistry, the field of photonics is actively exploring and utilizing it. A new family of 2D chiral lattices constructed from fully achiral unit cells is introduced here. This type of chiral structure differs fundamentally from previously reported arrays made of chiral unit cells. In this system, circular dichroism (CD) appears due to the electromagnetic interaction between unit cells and the formation of lattice plasmons (LP). Importantly, the CD is strongly enhanced for anisotropic rectangular lattices, whereas the chiral signal in square lattices is found to be relatively weak. The results cover two configurations. The first has an index‐matched environment, and the second includes an asymmetric arrangement of refractive indices. The index‐matched model is preferable and supports ultrasharp LP resonances. Overall, excellent control of the spectral position and broadening of the CD peaks is also demonstrated by tuning the geometry and matrix refractive indices. These results can be useful for engineering polarization filters and chiral biosensors. [ABSTRACT FROM AUTHOR]

Gold nanowires (AuNWs) have been one of the key components for nanoelectronics and optoelectronic devices but the fabrication has been poorly customized for this purpose even though diverse synthetic strategies bloomed over the last decades. Here, the concept of light‐induced protrusion of AuNWs directly from solid state substrate is demonstrated, which is highly compatible for on‐chip fabrication of functional nanodevices. This is realized by irradiating the Au ion‐doped titanium dioxide (TiO2) films with continuous wave laser. The blue laser triggers the reduction and nucleation of Au(0) which grows vertically into AuNW bundles with diffusion‐controlled supply of Au ions within the TiO2 matrix. Thus, the morphology of the AuNWs can be tuned with irradiation time/power as well as the ion concentration, which can derive into Au nanorings (NRs) and NR stacks in 1D photonic crystal with reduced plasmon linewidth. Such light‐induced protrusion can also generate nanopillars by introducing Au seeds before irradiation. The surface‐enhanced Raman scattering performance of the AuNW bundles is excellent with fm detection limit. Such laser‐directed solid‐state growth technique is facile, versatile, cost‐effective site‐selective, ligand‐free, and wafer‐scalable, which opens up many promising applications in (bio)chemical sensing, photovoltaics, photocatalysis, plasmonic displays, and integrated nanoelectronic/optoelectronic devices. [ABSTRACT FROM AUTHOR]