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Circular Dichroism in Low-Cost Plasmonics: 2D Arrays of Nanoholes in Silver
摘要： Arrays of nanoholes in metal are important plasmonic devices, proposed for applications spanning from biosensing to communications. In this work, we show that in such arrays the symmetry can be broken by means of the elliptical shape of the nanoholes, combined with the in-plane tilt of the ellipse axes away from the array symmetry lines. The array then di?erently interacts with circular polarizations of opposite handedness at normal incidence, i.e., it becomes intrinsically chiral. The measure of this di?erence is called circular dichroism (CD). The nanosphere lithography combined with tilted silver evaporation was employed as a low-cost fabrication technique. In this paper, we demonstrate intrinsic chirality and CD by measuring the extinction in the near-infrared range. We further employ numerical analysis to visualize the circular polarization coupling with the nanostructure. We ?nd a good agreement between simulations and the experiment, meaning that the optimization can be used to further increase CD.
关键词： nanoholes,plasmonics,circular dichroism,chirality
更新于2025-09-23 15:19:57
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Switching the Optical Chirality in Magnetoplasmonic Metasurfaces Using Applied Magnetic Fields
摘要： Chiral nanophotonic devices are promising candidates for chiral molecule sensing, polarization of diverse nanophotonics, and display technologies. Active chiral nanophotonic devices, where the optical chirality can be controlled by an external stimulus has triggered great research interest. However, efficient modulation of the optical chirality has been challenging. Here, we demonstrate switching of the extrinsic chirality by applied magnetic fields in a magnetoplasmonic metasurface device based on a magneto-optical oxide material, Ce1Y2Fe5O12 (Ce:YIG). Due to the low optical loss and strong magneto-optical effect of Ce:YIG, we experimentally demonstrated giant and continuous far-field circular dichroism (CD) modulation by applied magnetic fields from ?0.6 ± 0.2° to +1.9 ± 0.1° at 950 nm wavelength under glancing incident conditions. The far-field CD modulation is due to both magneto-optical circular dichroism and near-field modulation of the superchiral fields by applied magnetic fields. Finally, we demonstrate magnetic-field-tunable chiral imaging in millimeter-scale magnetoplasmonic metasurfaces fabricated using self-assembly.
关键词： optical chirality,magneto-optical effect,magnetoplasmonic,metasurface,circular dichroism,magnetic oxides
更新于2025-09-23 15:19:57
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Chirality-enabled unidirectional light emission and nanoparticle detection in parity-time-symmetric microcavity
摘要： Achieving unidirectional emission and manipulating waves in a microcavity are crucial for information processing and data transmission in next-generation photonic circuits (PCs). Here we show how to impose twin microcavities with opposite chirality by incorporating parity-time (PT) symmetry to realize unidirectional emission. Our numerical calculation results show that the opposite chirality in microcavities stems from the asymmetric coupling of the clockwise (CW) and counterclockwise (CCW) components carried by the attached waveguide to the left- or right-sided microcavities, respectively. Notably, by engineering PT symmetry in the coupled system via the gain-loss control, the clockwise component of the lossy cavity could be selectively suppressed, which leads to the unidirectional emission with an extinction ratio of up to ?52 dB. Furthermore, the chirality and PT-symmetry breaking enabled unidirectional emission is extremely sensitive to external scatters, allowing the detection of nanoparticles with an ultrasmall radius of 5–50 nm by recording the extinction ratio change. The proposed system provides a simple yet general way to manipulate the standing waves in a microcavity and will be essential for advancing the potentials of the microcavity in PCs.
关键词： unidirectional emission,nanoparticle detection,chirality,parity-time symmetry,microcavity
更新于2025-09-19 17:13:59
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Uniform Chiral Gap Synthesis for High Dissymmetry Factor in Single Plasmonic Gold Nanoparticle
摘要： Synthesis of chiral plasmonic material has been highlighted for the last decades with its optical properties and versatile potential applications. Recently reported aqueous based amino- acid-and peptide-directed synthesis of chiral plasmonic gold nanoparticles with 432 point-group symmetry shows exceptionally high chiroptic response within 100 nm scales. Despite its already excellent chiroptic response, single nanoparticle dark field scattering study revealed that full chiroptic potential of chiral gold nanoparticle is limited with its overall synthetic uniformity. Based on this knowledge, we present a multi-chirality-evolution step synthesis method for the enhancement of chiroptic response through increase in particle uniformity. Detailed time variant study and interrelationship study of reaction parameters allowed the systematic construction of design principles for chiral nanoparticle with exceptional chiroptic response. With the application of precisely controlled growth kinetic to two distinct growth regimes, modified chiral gold nanoparticle showed significantly improved uniformity, achieving improved dis-symmetry factor of g = 0.31. We expect that our strategy will aid in precise morphology and property control for chiral nanomaterials which to be used in various plasmonic metamaterial applications.
关键词： chiral nanoparticle,chirality,seed-mediated method,plasmonic nanoparticle,dissymmetric factor
更新于2025-09-19 17:13:59
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Binaphthyl-Based Macrocycles as Optical Sensors for Aromatic Diphenols
摘要： The synthesis of several rigid, homochiral organic macrocycles possessing, respectively, average molecular D2 and D3 symmetries, is described. They have been obtained from aromatic dicarboxylic acids, in combination with an axially-chiral, suitable dibenzylic alcohol, derived from 1,1′-binaphthyl-2,2′-diol (BINOL) using one-pot esterification reactions in good isolated yields. NMR and circular dichroism (CD) spectroscopies detect the structural and shape variability in the scaffolds, reflected both in terms of the changes in chemical shifts and the shape of selected proton resonances, and in terms of the variation of the CD signature related to the dihedral angle defined by the binaphthyl units embedded in the rigid cyclic skeleton. The D2 cyclic adducts are able to form stable complexes with aromatic diphenols, with binding strengths that are dependent on small variations in the spacing units, and therefore on the shapes of the internal cavities of the cyclic structures.
关键词： binaphthyl,macrocycles,chirality,circular dichroism,chiroptical sensors
更新于2025-09-19 17:13:59
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Preorganized helical chirality controlled homochiral self-assembly and circularly polarized luminescence in a quadruple-stranded Eu2L4 helicate
摘要： The homochiral quadruple-stranded helicate, ΔΔ-(Eu2L4) assembled from the bis-β-diketone with the preorganized helical chirality shows strong circularly polarized luminescence.
关键词： preorganized helical chirality,circularly polarized luminescence,homochiral,bis-β-diketone,quadruple-stranded helicate
更新于2025-09-19 17:13:59
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In Situ Investigation on the Protein Corona Formation of Quantum Dots by Using Fluorescence Resonance Energy Transfer
摘要： A fundamental understanding of nanoparticle–protein corona and its interactions with biological systems is essential for future application of engineered nanomaterials. In this work, fluorescence resonance energy transfer (FRET) is employed for studying the protein adsorption behavior of nanoparticles. The adsorption of human serum albumin (HSA) onto the surface of InP@ZnS quantum dots (QDs) with different chirality (d- and l-penicillamine) shows strong discernible differences in the binding behaviors including affinity and adsorption orientation that are obtained upon quantitative analysis of FRET data. Circular dichroism spectroscopy further confirms the differences in the conformational changes of HSA upon interaction with d- and l-chiral QD surfaces. Consequently, the formed protein corona on chiral surfaces may affect their following biological interactions, such as possible protein exchange with serum proteins plasma as well as cellular interactions. These results vividly illustrate the potential of the FRET method as a simple yet versatile platform for quantitatively investigating biological interactions of nanoparticles.
关键词： serum proteins,quantum dots,chirality,nanoparticle–protein interactions,protein corona,fluorescence resonance energy transfer
更新于2025-09-19 17:13:59
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Photonic bands, superchirality, and inverse design of a chiral minimal metasurface
摘要： Photonic band structures are a typical fingerprint of periodic optical structures, and are usually observed in spectroscopic quantities such as transmission, reflection, and absorption. Here we show that the chiro-optical response of a metasurface constituted by a lattice of non-centrosymmetric, L-shaped holes in a dielectric slab shows a band structure, where intrinsic and extrinsic chirality effects are clearly recognized and connected to localized and delocalized resonances. Superchiral near-fields can be excited in correspondence to these resonances, and anomalous behaviors as a function of the incidence polarization occur. Moreover, we have introduced a singular value decomposition (SVD) approach to show that the above mentioned effects are connected to specific fingerprints of the SVD spectra. Finally, by means of an inverse design technique we have demonstrated that the metasurface based on an L-shaped hole array is a minimal one. Indeed, its unit cell geometry depends on the smallest number of parameters needed to implement arbitrary transmission matrices compliant with the general symmetries for 2d-chiral structures. These observations enable more powerful wave operations in a lossless photonic environment.
关键词： chirality,polarization,inverse design,metasurface
更新于2025-09-16 10:30:52
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34.3: <i>Invited Paper:</i> Printing Pixel Circuits on Light Emitting Diode Array for AMLED Displays
摘要： An active matrix light emitting display module integrated with carbon nanotubes control circuits was fully printed. The high performance of super pure single-chirality carbon nanotube TFT provides super bright and low power consumption technologies for indoor and outdoor augmented reality that are highly desirable for civil and military display applications.
关键词： Aerosol Jet Printing,Active Matrix LED Display Module,Single Chirality Semiconducting Single-Walled Carbon Nanotubes,Thin Film Transistors,Light Emitting Diode Array
更新于2025-09-16 10:30:52
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Chirality control for predominant metallic or semiconducting single-walled carbon nanotubes prepared using a mild etchant
摘要： Highly oriented metallic and semiconducting SWCNTs were synthesized with different carrier gas compositions and etchants by the floating catalyst chemical vapor deposition method. The addition of acetone as an etchant resulted in metallic nanotubes. The acetone acted as both an additional carbon source and etching agent for carbon nanotube nucleation.
关键词： Chirality control,Metallic,Floating catalyst chemical vapor deposition,Single-walled carbon nanotubes,Acetone,Semiconducting,Etchant
更新于2025-09-16 10:30:52