Deepshikha Arora

Tailoring light-matter interaction using photonic modes depends on both the spectral and spatial overlap between the modes and quantum emitters, which is critical for optimizing light-matter coupling and enabling efficient, controllable emission. Here, we demonstrate deterministic control of emission from colloidal quantum dots (CQDs) integrated into dielectric light-emitting metasurfaces (LEMs) by precisely localizing the emitters at the field maxima of the photonic modes across the entire metasurface. Numerical simulations show that deterministic localization enhances the emission, yielding a higher emission enhancement factor than that of LEMs with randomly distributed emitters. Experimentally, such global spatial overlap is achieved using a single-template lift-off process to localize the CQDs at the desired positions. Optical characterization confirms efficient coupling between CQD emission and the photonic modes, resulting in a narrowed spectral linewidth and highly directional out-of-plane emission. Deterministic emission control in metasurfaces adds a new degree of freedom to LEM design, paving the way for an efficient integrated light source for classical and quantum photonic devices.

Optical microcavities are widely used to confine photons for exciton-polariton formation. However, their compact design often imposes limitations on spatial freedom, particularly in controlling the cavity length with the nanometer precision required for effective coupling with excitons. Existing methods for tuning resonances by integrating cavities with dynamic structures often lack sufficient resolution or a complex operation. Here, we introduce a multiresonant microcavity array that provides a full spectral selection of cavity resonances with a sub-5 nm cavity length variation. We employed this platform to investigate room-temperature polariton formation using gradient core-crown colloidal quantum wells that host highly stable excitons. The strong coupling system exhibits longevity of Rabi oscillations with a quality factor of Q_R = 3.3 and a large Rabi splitting exceeding twice the thermal losses. Notably, we achieved control of the polariton mixed properties across the cavity arrays on a single substrate. This platform is promising for the development of on-chip polaritonic devices.

The template-assisted saturated-vapor drop casting method achieves deterministic spatial localization of few to single aqueous silica-cladded colloidal quantum dots, yielding ~40% single-particle yield and ~80% total site occupancy.

The careful arrangement of nanomaterials (NMs) holds promise for revolutionizing various fields, from electronics and biosensing to medicine and optics. This review delves into the intricacies of nano-assembly (NA) techniques, focusing on oriented-assembly methodologies and stimuli-dependent approaches. The introduction provides a comprehensive overview of the significance and potential applications of NA, setting the stage for review. The oriented-assembly section elucidates methodologies for the precise alignment and organization of NMs, crucial for achieving desired functionalities. The subsequent section delves into stimuli-dependent techniques, categorizing them into chemical and physical stimuli-based approaches. Chemical stimuli-based self-assembly methods, including solvent, acid–base, biomolecule, metal ion, and gas-induced assembly, are discussed in detail by presenting examples. Additionally, physical stimuli such as light, magnetic fields, electric fields, and temperature are examined for their role in driving self-assembly processes. Looking ahead, the review outlines futuristic scopes and perspectives in NA, highlighting emerging trends and potential breakthroughs. Finally, concluding remarks summarize key findings and underscore the significance of NA in shaping future technologies. This comprehensive review serves as a valuable resource for researchers and practitioners, offering insights into the diverse methodologies and potential applications of NA in interdisciplinary research fields.

Efforts to increase the number of filters are driven by the demand for miniaturized spectrometers and multispectral imaging. However, processes that rely on sequential fabrication of each filter are cost ineffective. Herein, we introduce an approach to produce at least 16 distinct filters based on a single low‐resolution lithographic step with minimum feature size of 0.6 μm. Distinct from grayscale lithography, we employ standard binary lithography but achieve height variations in polymeric resist through a post‐development reflow process. The resulting transparent polymeric films were incorporated in Fabry–Perot cavity structures with cavity thickness ranging from 90 to 230 nm to produce transmittance across the visible spectrum. This binary lithography and reflow (BLR) process demonstrates control of the dielectric layer thickness down to ∼15 nm. This new process provides a cost‐effective alternative to traditional techniques in fabricating microscopic transmission filters, and other applications where precise thickness variation across the substrate is required.

Two-photon polymerization lithography is promising for producing three-dimensional structures with user-defined micro- and nanoscale features. Additionally, shrinkage by thermolysis can readily shorten the lattice constant of three-dimensional photonic crystals and enhance their resolution and mechanical properties; however, this technique suffers from non-uniform shrinkage owing to substrate pinning during heating. Here, we develop a simple method using poly(vinyl alcohol)-assisted uniform shrinking of three-dimensional printed structures. Microscopic three-dimensional printed objects are picked and placed onto a receiving substrate, followed by heating to induce shrinkage. We show the successful uniform heat-shrinking of three-dimensional prints with various shapes and sizes, without sacrificial support structures, and observe that the surface properties of the receiving substrate are important factors for uniform shrinking. Moreover, we print a three-dimensional mascot model that is then uniformly shrunk, producing vivid colors from colorless woodpile photonic crystals. The proposed method has significant potential for application in mechanics, optics, and photonics.

Tunable structural colors have a multitude of applications in the beautification of mobile devices, in the decoration of artwork, and in the creation of color filters. In this paper, we describe a Metal-Insulator-Metal (MIM) design that can be used to systematically tune structural colors by altering the thickness of the top metal and intermediate insulator. Cu and Si₃N₄ were selected as the top metal and intermediate insulator layers, respectively, and various reflection colors were printed on Al. To protect the Cu surface from scratchiness and oxidation, a number of capping layers, including SiO₂, LPSQ, PMMA, and the commercially available clear coat ProtectaClear, were applied. In addition to their ability to protect Cu from a humid environment without deteriorating color quality, ProtectaClear and LPSQ coatings have minimal angle dependency. Furthermore, a bilayer of PMMA/SiO₂ can protect the Cu surface from the effects of humidity. In addition, the PMMA/SiO₂ and ProtectaClear/SiO₂ bilayers can also protect against corrosion on the Cu surface. The colors can be tuned by controlling the thickness of either the metal layer or intermediate insulator layer, and vivid structural colors including brown, dark orange, blue, violet, magenta, cyan, green-yellow, and yellow colors can be printed. The measured dielectric functions of Cu thin films do not provide any evidence of the plasmonic effect, and therefore, it is expected that the obtained colors are attributed to thin-film interference.