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Uniaxial strain has been widely used as a powerful tool for investigating and controlling the properties of quantum materials. However, existing strain techniques have so far mostly been limited to use with bulk crystals. Although recent progress has been made in extending the application of strain to two-dimensional van der Waals (vdW) heterostructures, these techniques have been limited to optical characterization and extremely simple electrical device geometries. Here, we report a piezoelectric-based in situ uniaxial strain technique enabling simultaneous electrical transport and optical spectroscopy characterization of dual-gated vdW heterostructure devices. Critically, our technique remains compatible with vdW heterostructure devices of arbitrary complexity fabricated on conventional silicon/silicon dioxide wafer substrates. We demonstrate a large and continuously tunable strain of up to − 0.15% at millikelvin temperatures, with larger strain values also likely achievable. We quantify the strain transmission from the silicon wafer to the vdW heterostructure, and further demonstrate the ability of strain to modify the electronic properties of twisted bilayer graphene. Our technique provides a highly versatile new method for exploring the effect of uniaxial strain on both the electrical and optical properties of vdW heterostructures and can be easily extended to include additional characterization techniques. [ABSTRACT FROM AUTHOR]

Since 2017, the Institute for Nanotechnology Innovation at Rhodes University has studied the optical limiting properties of boron dipyrromethene (BODIPY) dyes with respect to high-intensity nanosecond timescale laser pulses. Concerns over the irresponsible use of laser pointers in the context of aviation safety have provided a need for materials that can readily transmit light under ambient conditions while rapidly attenuating intense incident laser pulses. The structural flexibility of the BODIPY chromophore facilitates the red shift of the main BODIPY spectral band that typically lies at ca. 500 nm to the red end of the visible and the near-infrared through the introduction of vinylene groups at the 3,5-positions or an aza-nitrogen atom. Research carried out in this context is described, and possible future directions are discussed. [ABSTRACT FROM AUTHOR]

Bismuth-modified lead silicate glasses with composition 20PbO∙(80-x)Bi2O3∙xSiO2 (10 ≤ x ≤ 40 mol%) were fabricated by classical melt-quench technique. The density (D), crystalline volume (VC), and molar volume (VM) values decrease with a decrease in bismuth concentration. FTIR spectra suggest the formation of [BiO3], [BiO6], [SiO4], [PbO3], and [PbO4] structural units. The optical band gap (Eg) values for the studied glass composition are determined to be between 1.93 and 2.12 eV, while their Urbach energy (∆E) values fall between 0.14 and 0.24 eV. A decrease in values of average electronic oxide polarizability (2.84‒1.62 Å3), and optical basicity (1.08‒0.64), predict the increase in the covalence nature of the Bi-O bond with the incorporation of SiO2 in the glass network. The small metallization criterion (0.311 to 0.325) predicts the suitability of the prepared series to be utilized as nonlinear optical materials. The Z-scan approach was utilized to determine the third-order nonlinear optical characteristics, including the nonlinear absorption coefficient (α2), nonlinear susceptibility (χ(3)), and nonlinear refractive index (η2). Optical studies reveal that with the decrease in Bi2O3 content, nonbridging oxygens (NBOs) decrease leads to an increase in bandgap and a drop in the nonlinear refractive index. The dynamic range (DR) and limiting threshold values have also been reported from the optical limiting studies of the prepared glasses. [ABSTRACT FROM AUTHOR]

Boron-β-diketonates are classical emissive materials that have been utilized in various fields, however, boron monothio-β-thioketonates, where one oxygen atom is exchanged for a sulphur atom, have not been explored in detail. To gain a better understanding of this class of materials, we synthesised various aryl substituted monothio-β-diketonate boron complexes with two different aryl substitutions on the boron center and studied their structural, optical and electrochemical properties. Single crystal X-ray analysis revealed that there is considerable deviation in B–O and B–S bond lengths for bis(pentafluorophenyl)boron complexes against diphenyl boron complexes. The bis(pentafluorophenyl)boron complexes have a relatively high absorption coefficient over diphenyl boron complexes. More importantly, a striking difference was observed for the emission behaviour of these compounds. The bis(pentafluorophenyl)boron complexes exhibit weak emission in the solution as well as in the solid state, whereas diphenyl boron complexes do not show any emission in either solution or the solid state. Further, the electrochemical study reveals that diphenyl boron complexes show a reduction potential that is more negative compared to the bis(pentafluorophenyl)boron complexes. The high absorption coefficient of the compounds pointed towards the possibility of high first order hyperpolarizability upon optical excitation, which motivated us to ascertain the nonlinear optical coefficients in the near infrared range, towards applicability of such compounds in optical limiting and switching. The open aperture Z-scan measurements at ultrashort time scales elucidated a few critical features of such compounds towards optical limiting applications. [ABSTRACT FROM AUTHOR]

The aqueous solution cast method was used to create the biodegradable polymer nanocomposite (PNC) films from a blend of poly (vinyl alcohol) PVA and poly (vinyl pyrrolidone) PVP (70/30 wt %) and Fe2O3 nanoparticles (NPs). These PNC films were characterized using X-ray diffraction, scanning electron microscopy SEM, Fourier transform infrared spectroscopy FTIR, and ultraviolet-visible spectroscopy. XRD and FTIR results indicate that Fe+ 3 NPs interact with the host polymer. Optical, electrical, mechanical, and radiation shielding measurements were performed on the PNC films. From the optical measurements, the indirect optical band gap drops from 4.86 eV for the pure blend to 4.26 eV at the greatest NPs concentration. Optical limiting characterization shows that the output power of He-Ne and solid-state green laser beams is reduced from 22.98 to 3.6 mW and 6.59 to 1.4 mW, respectively, when the Fe2O3 NPs content in the blend matrix is increased to 6 wt %. The NGCal software was utilized to calculate nuclear radiation shielding properties. The findings demonstrated that when the concentration of Fe2O3 rose, the PNC films half-value layer and mean free path decreased. Mechanical measurements demonstrate that increasing the Fe2O3 content significantly improves nanocomposite films' yield and tensile strength. Tensile strength is measured at 27.03 MPa for the composite film containing 6 wt % Fe2O3, which is significantly higher than the 8.66 MPa of the pure (PVA-PVP) film. Compared to the other samples under examination, the 6 wt % Fe2O3 sample yielded the best results (based on the analyzed optical, electrical, mechanical, and radiation shielding properties). [ABSTRACT FROM AUTHOR]

Simultaneously optimizing nonlinear absorption coefficient and modulation depth is a considerable challenge for nonlinear optical materials. Here we present an effective solution through constructing PbS2‐based inorganic‐organic superlattice. PbS2/Cn superlattice particles are synthesized, where n (4, 6, and 8) denotes the number of carbon atoms in the organic component. First‐principles simulations indicate the formation of covalent bonds and van der Waals interaction between PbS2 unit and interlayer organic molecules. All samples exhibit strong nonlinear absorption under femtosecond laser excitation with a wavelength range between 515 nm and 900 nm, and the nonlinear absorption coefficient increases with interlayer distance. The optimized sample, PbS2/C8, demonstrates outstanding nonlinear absorption and substantial modulation depth under 800 nm (the third‐order nonlinear absorption coefficient βeff, 10449 ± 609 cm GW−1; modulation depth, 39.1%) and 900 nm (the fifth‐order nonlinear absorption coefficient γeff, 6465 ± 68 cm3 GW−2; modulation depth, 88.1%), which exhibits saturable absorption under 515 nm (βeff, ‐4932 ± 818 cm GW−1; modulation depth, 48.1%). It exhibits a small optical limiting threshold of 1.23 mJ cm−2. These performances surpass those of typical single‐/few‐layer metal chalcogenides. Structural and spectral analyses elucidate that the remarkable optical nonlinearity can be attributed to quantum confinement in the inorganic layer and the dielectric enhancement of the superlattice. [ABSTRACT FROM AUTHOR]

The mammalian plasma membrane is known to contain domains with varying lipid composition and biophysical properties. However, studying these membrane lipid domains presents challenges due to their predicted morphological similarity to the bulk membrane and their scale being below the classical resolution limit of optical microscopy. To address this, we combine the solvatochromic probe di-4-ANEPPDHQ, which reports on its biophysical environment through changes in its fluorescence emission, with spectrally resolved single-molecule localisation microscopy. The resulting data comprises nanometre-precision localisation coordinates and a generalised polarisation value related to the probe's environment – a marked point pattern. We introduce quantification algorithms based on topological data analysis (PLASMA) to detect and map nano-domains in this marked data, demonstrating their effectiveness in both artificial membranes and live cells. By leveraging environmentally sensitive fluorophores, multi-modal single molecule localisation microscopy, and advanced analysis methods, we achieve nanometre scale mapping of membrane properties and assess changes in response to external perturbation with methyl-β-cyclodextrin. This integrated methodology represents an integrated toolset for investigating marked point pattern data at nanometre spatial scales. Studying lipid nano-domains within the mammalian cell plasma membrane remains a very challenging task. Here, the authors use the solvatochromic probe di-4-ANEPPDHQ, which is sensitive to its biophysical environment, to map membrane nano-environments via single-molecule localisation microscopy. [ABSTRACT FROM AUTHOR]

Mechanically interlocked molecules, such as rotaxanes, have drawn significant attention within supramolecular chemistry. Although a variety of macrocycles have been thoroughly explored in rotaxane synthesis, metal‐organic macrocycles remain relatively under‐investigated. Aluminum molecular rings, with their inner cavities and numerous binding sites, present a promising option for constructing rotaxanes. Here, we introduce an innovative "ring‐donor⋅⋅⋅axle‐acceptor" motif utilizing Al8 molecular rings, enabling the stepwise assembly of molecules, complexes, and polymers through tailored coordination chemistry. This novel approach can not only be applied to macrocycle‐based systems like catenanes but also enhance specific functionalities progressively. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Macrocyclic compounds are of great interest for their ability to capture guest molecules into their cavities. In particular, host‐guest interaction plays a crucial role in the formation of supramolecular compounds. Herein, two host‐guest supramolecular compounds, [Al8(OH)8(L)16]·2HL (HL@AlOC‐166, HL = 4‐Iodobenzoic acid) and [Al8(OH)8(L)8(L1)8]·2DMF (DMF@AlOC‐166, HL1 = isoamyl alcohol), are acquired by introducing different types of guest components based on the internal pore cavities of the aluminum molecular ring [Al8(OH)8(L)16] (AlOC‐166). The inclusion of these guests is attributed to the presence of abundant hydrophilic OH serving as the hydrogen bond donors inward the ring cavity. Host‐guest compounds usually exhibit superior nonlinear optical (NLO) response due to the existence of guest molecules that could change symmetry, dipole moments, charge distributions, etc. Unexpectedly, the AlOC‐166 achieved the best NLO results, although it had no guest molecules inside its molecular ring, which breaks the traditional concept. The reason for this trend can be explained by the difference in intermolecular force rather than intramolecular interaction, mainly related to the amount and strength of π···π and C—I···π interactions in different compounds. This work investigates the effect of host‐guest interaction on NLO, representing a new perspective for designing optical limiting materials. [ABSTRACT FROM AUTHOR]

Comprehensive Summary: Macrocyclic compounds are of great interest for their ability to capture guest molecules into their cavities. In particular, host‐guest interaction plays a crucial role in the formation of supramolecular compounds. Herein, two host‐guest supramolecular compounds, [Al8(OH)8(L)16]·2HL (HL@AlOC‐166, HL = 4‐Iodobenzoic acid) and [Al8(OH)8(L)8(L1)8]·2DMF (DMF@AlOC‐166, HL1 = isoamyl alcohol), are acquired by introducing different types of guest components based on the internal pore cavities of the aluminum molecular ring [Al8(OH)8(L)16] (AlOC‐166). The inclusion of these guests is attributed to the presence of abundant hydrophilic OH serving as the hydrogen bond donors inward the ring cavity. Host‐guest compounds usually exhibit superior nonlinear optical (NLO) response due to the existence of guest molecules that could change symmetry, dipole moments, charge distributions, etc. Unexpectedly, the AlOC‐166 achieved the best NLO results, although it had no guest molecules inside its molecular ring, which breaks the traditional concept. The reason for this trend can be explained by the difference in intermolecular force rather than intramolecular interaction, mainly related to the amount and strength of π···π and C—I···π interactions in different compounds. This work investigates the effect of host‐guest interaction on NLO, representing a new perspective for designing optical limiting materials. [ABSTRACT FROM AUTHOR]

We report here a novel family of ylidic P‐heteroarenes (P1–P6), structurally featuring unique phosphonium cyclopentadienylide (P−Cp)‐fused π‐skeletons and synthetically prepared via an unexpected one‐pot [2+3]/[3+3] phospha‐annulation reaction. While the facile and modular synthesis allows the fine‐tuning of their optical absorptions and redox properties, single‐crystallographic and theoretical analysis of these P‐heteroarenes further reveal that the fusion of P−Cp moiety leads to substantial intramolecular charge‐separated features with high ylidic character values of up to 84 %. Benefitted from such dipolar structures, these P‐heteroarenes not only allows stepwise electrophilic substitution reaction for further structural π‐expansions, but also exhibit excellent nonlinear optical (NLO) responses and optical limiting (OL) performances comparable to or exceed those of C60. As a model compound, the persistent radical‐anion salt of P5a was also prepared through chemical reduction, thus offering valuable insights into the electronic structures of reduced P‐ylidic species. Our work not only established a highly efficient synthetic method toward new P‐heteroarenes, but also provide fundamental understanding of those fused‐ring ylidic P‐heterocycles with promising NLO/OL applications. [ABSTRACT FROM AUTHOR]

This research presents the optical limiting properties of a novel axially linked D‐A type compound, LaPc‐C60(OH)n, where lanthanide phthalocyanine serves as the donor and fullerenol as the acceptor. The incorporation of fullerenol expands the π‐conjugated system, decreases the aggregation of the phthalocyanine, and significantly increases the solubility of the compound. The establishment of this D‐A system promotes intramolecular electron transfer, effectively improving both the non‐linear optical (NLO) response and optical limiting properties. In addition, homogeneous poly(methyl methacrylate) (PMMA) composite films (LaPc‐C60(OH)n/PMMA) are prepared using a simple solution casting method. Compared to fullerenol or lanthanum phthalocyanine individually, LaPc‐C60(OH)n exhibited a superior NLO response both in solution and in the solid composite film. In particular, LaPc‐C60(OH)n/PMMA demonstrated an increase in the non‐linear absorption coefficient (2050 cm GW−1) and a larger third‐order magnetization (1.84 × 10−8 esu). In addition to exhibiting an excellent NLO response at 532 nm, LaPc‐C60(OH)n also shows significant NLO enhancement at 1064 nm, extending the limiting range into the near‐infrared region. This behavior is attributed to different nonlinear absorption mechanisms and the synergistic effect that arise from the photo‐induced electron transfer process between the fullerenol and LaPc. [ABSTRACT FROM AUTHOR]

Dimensionality of covalent organic frameworks (COFs), in terms of 2D and 3D, must greatly influence their properties and functionalities due to the different electronic and porous structures, but still less investigated in the 20 years history. Herein, on the basis of the imidization reaction of phthalocyanine‐based tetraanhydride monomers with either 1,4‐phenylenediamine or 1,3,5,7‐tetra(4‐aminophenyl)adamantine, 2D and 3D imide‐bonded COFs with sql and pts topology have been prepared to explore their third‐order nonlinear optical (NLO) properties. In contrast to metal‐free analogues, both 2D and 3D copper‐phthalocyanine COFs have the enhanced NLO behaviors according to the open aperture Z‐scan and optical limiting (OL) results recorded under a nanosecond laser at 532 nm. In particular, 2D COFs with strong π–π staking phthalocyanine units show the NLO property with bigger third‐order nonlinear susceptibility (Imχ(3)) and unique reverse saturation absorption response at 1064 nm than that of 3D species with dispersed conjugated modules. Furthermore, femtosecond transient absorption spectra disclose the longer excited lifetimes of copper COFs than metal free samples, helpful in their NLO property. These findings clearly disclose the materials advantages of 2D phthalocyanine COFs toward the NLO characteristics and provide new candidates for OL application. [ABSTRACT FROM AUTHOR]

The investigation of nonlinear optical (NLO) properties is crucial for the effective application of CsPbI3/TiO2 nanocomposites in NLO devices. The CsPbI3/TiO2 nanocomposites were synthesized by a hot injection method. Then, the CsPbI3/TiO2 nanocomposites were poured into methyl methacrylate via polymerization to fabricate CsPbI3/TiO2/PMMA organic glasses (OGs). The crystal structure and size morphology of the CsPbI3/TiO2 nanocomposites were examined using X-ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The nonlinear absorption (NLA), nonlinear refraction (NLR), and optical limiting (OL) properties of the CsPbI3/TiO2/PMMA OGs were investigated by using the Z-scan technique, employing a nanosecond pulse laser operating at a wavelength of 532 nm. The CsPbI3/PMMA and CsPbI3/TiO2/PMMA OGs can be transferred from saturable absorption (SA) to reverse saturable absorption (RSA) by varying the incident energy. In addition, the CsPbI3/TiO2/PMMA OGs exhibit superior NLA, NLR, and OL performances compared to the CsPbI3/PMMA OG and other halide-based perovskites. The enhanced nonlinear optical (NLO) properties of CsPbI3/TiO2/PMMA OGs can be ascribed to the cooperative interaction between CsPbI3 and TiO2. In summary, the results indicate that CsPbI3/TiO2 nanocomposites possess substantial potential for applications in NLO devices such as optical limiters, optical switches, and optical modulators. [ABSTRACT FROM AUTHOR]

The nonlinear properties and photophysical dynamics of aluminum and zinc tetracarboxy-phthalocyanines (AlPc and ZnPc) were studied using pulse trains of a 532 nm wavelength, which contain 25 subpulses with a 100 ps width and 13 ns spacing. Considering its interaction with long-duration pulses, the energy structure of phthalocyanine could be substituted by a five-level pattern. The nonlinear transmissions of pulse trains in AlPc and ZnPc were simulated by means of equations about the population rate coupled with the paraxial field equation of two-dimensional space. The well-known Crank–Nicholson numerical method was applied to the theoretical simulation. The results demonstrate that both phthalocyanines are efficient as optical limiters. In its low-intensity region, AlPc shows a much better OL effect than ZnPc. But in the region with high intensity, their energy transmittances are nearly the same. The nonlinear transmission of a pulse is susceptible to the state lifetime and cross section of one-photon absorption. Tetracarboxy-phthalocyanines have advantageous photophysical properties for applications in nonlinear optical areas, such as nonlinear optical devices like optical limiters. Adding central metals such as Al and Zn to phthalocyanines could enhance their photodynamic properties, making them potential optical limiters and photosensitizers. [ABSTRACT FROM AUTHOR]

This article reports the in-situ growth of spinel CoCr 2 O 4 nanocrystals (NC) in tellurite glass through tailoring the Co content by melt-quenching method. The microstructure, optical, and magnetic properties of NC/ glass systems were systematically studied using various techniques. Well-defined 30 nm crystallization of CoCr 2 O 4 (space group of Fd3m) homogeneously distributed in the glassy matrix and the concurrent formation of cubic BiCoO 3 (space group of P4mm) when the Co content exceeds 3%. The coexistence of multivalence and coordination states of Co and Cr significantly modified the glass structure with conversion of TeO 4 →TeO 3 , BO 4 →BO 3 , and CoO 4 →CoO 6 units. Exceptional performance of the glass containing 5% Co-tuned CoCr 2 O 4 was obtained, showcasing the decrease of E g (2.09 eV), strong ferro-magnetization of 7.04 emu/g, large α 3 (4.88×10−10 m/W) and good optical limiting property (threshhold of 1.31×1012 W/m2). Furthermore, the same glass showed excellent red emission between 650 and 800 nm under the excitation of 460 nm, with an increased lifetime (2.648 ms) and good stability of 90.7% within 25–300 °C. The emission mechanism was discussed. EPR analysis confirmed the active role and spin-states of magnetic Cr and Co ions, contributing synergistically to the improved optical and magnetic properties of the glasses. [ABSTRACT FROM AUTHOR]

Brillouin spectroscopy has become an important tool for mapping the mechanical properties of biological samples. Recently, stimulated Brillouin scattering (SBS) measurements have emerged in this field as a promising technology for lower noise and higher speed measurements. However, further improvements are fundamentally limited by constraints on the optical power level that can be used in biological samples, which effectively caps the gain and signal-to-noise ratio (SNR) of SBS biological measurements. This limitation is compounded by practical limits on the optical probe power due to detector saturation thresholds. As a result, SBS-based measurements in biological samples have provided minimal improvements (in noise and imaging speed) compared with spontaneous Brillouin microscopy, despite the potential advantages of the nonlinear scattering process. Here, we consider how a SBS spectrometer can circumvent this fundamental trade-off in the low-gain regime by leveraging the polarization dependence of the SBS interaction to effectively filter the signal from the background light via the polarization pulling effect. We present an analytic model of the polarization pulling detection scheme and describe the trade-space unique to Brillouin microscopy applications. We show that an optimized receiver design could provide >25× improvement in SNR compared to a standard SBS receiver in most typical experimental conditions. We then experimentally validate this model using optical fiber as a simplified test bed. With our experimental parameters, we find that the polarization pulling scheme provides 100× higher SNR than a standard SBS receiver, enabling 100× faster measurements in the low-gain regime. Finally, we discuss the potential for this proposed spectrometer design to benefit low-gain spectroscopy applications such as Brillouin microscopy by enabling pixel dwell times as short as 10 μs. [ABSTRACT FROM AUTHOR]

Nonlinear absorption coefficient and modulation depth stand as pivotal properties of nonlinear optical (NLO) materials, while the existing NLO materials exhibit limitations such as low nonlinear absorption coefficients and/or small modulation depths, thereby severely impeding their practical application. Here we unveil that introducing Jahn–Teller distortion in a Mott‐Hubbard system, (MA)2CuX4 (MA=methylammonium; X=Cl, Br) affords the simultaneous attainment of a giant nonlinear absorption coefficient and substantial modulation depth. The optimized compound, (MA)2CuCl4, demonstrates a nonlinear absorption coefficient of (1.5±0.08)×105 cm GW−1, a modulation depth of 60 %, and a relatively low optical limiting threshold of 1.22×10−5 J cm−2. These outstanding attributes surpass those of most reported NLO materials. Our investigation reveals that a more pronounced distortion of the [CuX6]4− octahedron emerges as a crucial factor in augmenting optical nonlinearity. Mechanism study involving structural and spectral characterization along with theoretical calculations indicates a correlation between the compelling performance and the Mott‐Hubbard band structure of the materials, coupled with the Jahn–Teller distortion‐induced d‐d transition. This study not only introduces a promising category of high‐performance NLO materials but also provides novel insights into enhancing the performance of such materials. [ABSTRACT FROM AUTHOR]

In the present communication, binary (ZnO:Ga 2 O 3 - 1:1 (ZGO), ZnO:Ga 2 O 3 - 2:1 (GaZn))/ternary (EZG (Eu 2 O 3 : ZnO: Ga 2 O 3 (1:1:1)), MZG (MgO: ZnO: Ga 2 O 3 (1:1:1)) NCs are synthesized by P i p e r b e t l e leaves extract as a reducing agent followed by calcination at 600 °C for 3 h. The Bragg reflections confirms the formation of single phase cubic symmetry with F d 3 m space group in ZGO NCs whereas reflections related individual metal oxides are observed in the GaZn, EZG and MZG NCs. The irregular size and shaped nanoparticles are observed in all the synthesized NCs. The tuned band gap was found to be in the range of 3.08 to 3.11 eV. The optical nonlinearity of the specimens was analyzed using the open aperture Z-scan technique. The material demonstrated reverse saturable absorption attributed to a two-photon absorption (2PA) process. The non linear absorption coefficient follows the order MZG > GaZn > ZGO > EZG. However, the optical limiting threshold follows the order ZGO > GaZn > MZG > EZG NCs with increase in energy band gap. These outcomes distinctly indicate the superior potential of GaZn binary NCs for optical limiting applications. This characteristic is advantageous for shielding sensors and the human eye, safeguarding them against the detrimental effects of intense green laser radiation. [ABSTRACT FROM AUTHOR]

Deep insights into the complex cellular and molecular changes occurring during (patho‐)physiological conditions are essential for understanding the interactions and regulation of proteins. This understanding is crucial for research and diagnostics. However, the effectiveness of conventional immunofluorescence and light microscope, tools for visualizing the spatial distribution of cells or proteins, are limited both in resolution and multiplexity in complex tissues. This is mainly due to challenges such as the spectral overlap of fluorophore wavelengths, a limited range of antibody types, the inherent variability of samples and the optical resolution limit. The herein demonstrated combination of multiplex immunofluorescence imaging and super resolution microscopy offers a solution to these limitations by enabling the identification of different cell types and precise subcellular localization of proteins in tissue sections. In this study, we demonstrate the cyclic staining and de‐staining of paraffin kidney sections, making it suitable for routine use and compatible with super‐resolution microscopy for podocyte ultrastructural studies. We have further developed a computerized workflow for data processing which is accessible through available reagents and open‐access code. As a proof of principle, we identified CDH2 as a marker for cellular lesions of sclerotic glomeruli in the nephrotoxic serum nephritis mouse model and cross‐validated this finding with a human Nephroseq dataset indicating its translatability. In summary, our work represents an advance in multiplex imaging, which is crucial for understanding the localization of numerous proteins in a single FFPE kidney section and the compatibility with super‐resolution microscopy to study ultrastructural changes of podocytes. [ABSTRACT FROM AUTHOR]

Multivalent ions, especially Al3+ in aqueous electrolyte contributes to higher capacity and color contrast for more sustainable post‐lithium electrochromism and energy storages. However, the lack of suitable cathodic and anodic electrochromic materials is a major challenge for Al‐ion electrochromic batteries, which limits their optical contrast and lifespan. Herein, we report that Wadsley‐Roth phase Nb18W16O93 with open structure achieves Al3+ intercalation/extraction reversibly. The complementary electrochromic energy storage devices based on Nb18W16O93 coupled with Prussian blue using hybrid Al3+/K+ aqueous electrolytes show a fast response, a high capacity and a large coloring efficiency. The superior performances are due to the cations of Al3+ and K+ selectively insert/extract in the electrode of Nb18W16O93 and Prussian blue, respectively. This work provides an effective strategy for high‐performance and low‐cost electrochromic batteries with higher sustainability. [ABSTRACT FROM AUTHOR]

Treatment of [Et4N]2[WSe4] with three equivalents of CuCl and PPh3 (Ph = phenyl) in a mixed solvent of 25 mL of CH2Cl2 and 5 mL of DMF afforded a distorted cubane-like cluster [(µ-Cl)(µ3-WSe4)(CuPPh3)3] (1), which has been structurally characterized by single-crystal X-ray diffraction. The coordination geometry of the tungsten center and two copper atoms is tetrahedral, whereas that of the other copper atom is triangular. Regarding the NLO properties, a large optical limiting effect with a threshold of 0.91 J cm−2 was observed with laser pulses of 7 ns at 532 nm. [ABSTRACT FROM AUTHOR]

Regarded as an essential transition metal, gold holds significant research value in the academic realm. In this work, gold nanoparticles were prepared by a combination of magnetron sputtering and liquid-phase exfoliation. The nonlinear optical properties of gold nanoparticles had been systematically investigated by utilizing the open aperture Z-scan method with both nanosecond and picosecond laser sources, which were rarely involved in previous studies. Based on the saturation absorption properties of gold nanoparticles, we prepared a gold saturable absorber and successfully applied it in generating passively Q-switched pulses in Pr:YLF crystal laser and Nd:YAG crystal laser, respectively. And we also analyzed its optical limiting applications. Our systematic study confirms that gold nanoparticles are suitable as candidates for saturable absorbers and optical limiting materials. [ABSTRACT FROM AUTHOR]

Toroidal electromagnetic pulses have been recently reported as nontransverse, space-time nonseparable topological excitations of free space. However, their propagation dynamics and topological configurations have not been comprehensively experimentally characterized. In addition, the existing generators were limited in optical and terahertz domains; however, the feasibility and significance of generating such pulses at microwave frequencies have been overlooked. Here, we report that microwave toroidal pulses can be launched by a transient finite-aperture broadband horn antenna emitter, as an electromagnetic counterpart of "air vortex cannon." Applying this effective generator, we experimentally map the toroidal pulses' topological skyrmionic textures in free space and demonstrate their resilient propagation dynamics, i.e., how that, during propagation, the pulses evolve toward stronger space-time nonseparability and closer proximity to the canonical Hellwarth–Nouchi toroidal pulses. Our work offers a practical opportunity for using topologically robust toroidal pulses as information carriers in high-capacity telecom, cell phone technology, remote sensing, and global positioning, especially where microwave frequencies are predominant. [ABSTRACT FROM AUTHOR]

The successful growth of 2-Methylbenzimidazolium 4-nitrobenzoate 4-nitrobenzoic acid (MINB) from a solution of ethyl and methyl alcohol using the solvent evaporation solution technique (SEST). The MINB crystal belongs to the triclinic crystal system and possesses a centrosymmetric P-1 space group, maintained by N–H...O and O–H...O interactions. Proton configuration confirmation was achieved through 1H-NMR analysis, while FTIR and Raman studies identified functional groups and vibrational frequencies. Optical transmission analysis revealed exceptional transparency (> 90%), along with a cut-off wavelength at 400 nm and Eg = 2.91 eV. The crystal's thermal behaviour was studied using thermogravimetric and differential thermal analysis, etching studies assessed crystal perfection, Vicker's microhardness test determined load-dependent hardness, and dielectric properties (ε′, δ) were measured at 313 K with the frequency range of 50 Hz to 5 MHz. Nonlinear optical characteristics were explored using Q-switched Nd:YAG laser with a wavelength of 532 nm, exhibits Reverse saturable absorption (RSA) has been triggered by Two-Photon Absorption (2PA). The nonlinear absorption coefficient (β) of MINB crystal increased with concentration of solution, while the optical limiting threshold decreased with higher MINB concentrations, showcasing its intriguing properties and potential applications. We exploited First-principles density functional theory and ab-initio molecular dynamics simulations to investigate the electrical and optical characteristics of the MINB material. We establish that this material exhibits semiconductor properties, characterized by an energy band gap of 2.86 eV and notable absorption in the Ultraviolet (UV) light spectrum. [ABSTRACT FROM AUTHOR]

Quaternary (AlxGa1−x)yIn1−yP alloys grown on GaAs substrates have recently gained considerable interest in photonics for improving visible light-emitting diodes, laser diodes, and photodetectors. With two degrees of freedom (x, y) and keeping growth on a lattice-matched GaAs substrate, the (AlxGa1−x)0.5In0.5P alloys are used for tuning structural, phonon, and optical characteristics in different energy regions from far-infrared (FIR) → near-infrared (NIR) → ultraviolet (UV). Despite the successful growth of (AlxGa1−x)0.5In0.5P/n+-GaAs epilayers, limited optical, phonon, and structural characteristics exist. Here, we report our results of carefully examined optical and vibrational properties on highly disordered alloys using temperature-dependent photoluminescence (TD-PL), Raman scattering spectroscopy (RSS), and Fourier-transform infrared reflectivity (FTIR). Macroscopic models were meticulously employed to analyze the TD-PL, RSS, and FTIR data of the (Al0.24Ga0.76)0.5In0.5P/n+-GaAs epilayers to comprehend the energy-dependent characteristics. The Raman scattering and FTIR results of phonons helped analyze the reflectivity spectra in the FIR region. Optical constants were carefully integrated in the transfer matrix method for evaluating the reflectivity R (E) and transmission T (E) spectra in the NIR → UV regions, validating the TD-PL measurements of bandgap energies (E g P L) . [ABSTRACT FROM AUTHOR]

Augmented reality overlays computer-generated virtual information onto real-world scenes, enhancing user interaction and perception. However, traditional augmented reality optical systems are usually large, bulky, and have limited optical performance. In this paper, we propose a novel compact monochrome reflective dielectric metalens visor with see-through properties, engineered using a periodic structure of spin-dependent supercells. The supercell, which is composed of staggered twin nanofins, provides spin-dependent destructive or constructive interference with different circularly polarized incidences. The design combines the principles of interference with the Pancharatnam–Berry phase to enhance reflection at a working wavelength of 650 nm while maintaining good transmission. Right circularly polarized light incident from the substrate side causes destructive interference, enabling the supercell to work in reflection mode, while left circularly polarized light causes constructive interference, enabling the supercell to work in transmission mode. Furthermore, the supercell-constructed metalens can achieve near-diffraction-limited reflective focusing and a broad diagonal field of view of approximately 96°. In addition, compared to transmissive metalens visors, the reflective design eliminates the need for a beam splitter, significantly reducing the size and weight of the system. Our work could facilitate the development of compact and lightweight imaging systems and provide valuable insights for augmented reality near-eye display applications. [ABSTRACT FROM AUTHOR]

Treatment of [Et4N]2[WSe4] with three equivalents of CuCl and PPh3 (Ph = phenyl) in a mixed solvent of 25 mL of CH2Cl2 and 5 mL of DMF afforded a distorted cubane-like cluster [(µ-Cl)(µ3-WSe4)(CuPPh3)3] (1), which has been structurally characterized by single-crystal X-ray diffraction. The coordination geometry of the tungsten center and two copper atoms is tetrahedral, whereas that of the other copper atom is triangular. Regarding the NLO properties, a large optical limiting effect with a threshold of 0.91 J cm−2 was observed with laser pulses of 7 ns at 532 nm. [ABSTRACT FROM AUTHOR]

Abstract This study discusses the nonlinear optical properties of as-grown and annealed NiO thin films using the Z-scan technique utilizing the femtosecond laser pulses at a repetition rate of 100 kHz of wavelength 1030 nm with a pulse duration of 370 fs. In open aperture measurements, pristine reveal saturable absorption (SA) with a negative sign of nonlinearity, while annealed samples exhibit reverse saturable absorption (RSA) with a positive sign of nonlinearity. In closed aperture conditions, all samples show prefocal minima and postfocal maxima, indicating self-focusing behavior. The observed RSA phenomena are attributed to the indirect two-photon absorption (TPA) process. The influence of surface plasmon resonance on nonlinear absorption is successfully ruled out due to insufficient excitation energy (1.20 eV) to induce resonance in the samples. The increase in bandgap with annealing temperature, associated with indirect TPA, is elucidated with the shifting of Ni- $$d_{x^2-y^2}$$ d x 2 - y 2 and Ni- $$d_{z^2}$$ d z 2 orbitals in the conduction band, under the framework of Density Functional Theory (DFT). The DFT results are correlated with the observed nonlinear SA and RSA processes. The Ni d-d and Ni-d to O-p transitions contribute to the modulation of nonlinearity in the indirect TPA process. The study suggests that the sample annealed at 400 °C exhibits superior optical limiting properties with the highest nonlinear absorption coefficients compared to the other annealed sample, while the as-grown sample is suitable for passive Q-switching applications.

Abstract Graphene Quantum Dots (GQDs) are crucial in biomedicine for sensitive biosensing and high-resolution bioimaging and in photonics for their nonlinear optical properties. Integrating GQDs with photonic structures enhances optical properties by optimizing light-matter interactions and enabling precise control over their emission wavelengths. In this work, we explore a facile synthesis method for GQDs by pulsed laser irradiation in chlorobenzene and highlight the transformative potential of Tamm Plasmon Cavity (TPC) structures for tuning and amplifying the photoluminescence and nonlinear optical properties of GQDs. The characterization of GQDs revealed their exceptional properties, including efficient optical limiting and stable photoluminescence. The study demonstrated that the TPC structure significantly amplifies nonlinear optical effects due to the high light-matter interaction, indicating the potential for advanced optical systems, including optical limiters and nonlinear optical devices. Furthermore, introducing GQDs into the TPC structure leads to a significant enhancement and tuning of fluorescence emission. The Purcell effect, in combination with the confined electromagnetic fields within the TPC, increases the spontaneous emission rate of GQDs and subsequently enhances the fluorescence intensity. This enhanced and tunable fluorescence has exciting implications for high-sensitivity applications such as biosensing and single-molecule detection.

As manufacturing looks to employ more smart and autonomous processes to improve how items are made, reducing scrappage rates and with it the associated waste of time and energy, new ultra‐compact sensors are needed that can be deployed where existing instrumentation cannot. The use of traditional methods when constructing optical sensors limits the progress that can be made in reducing their size and weight, however, emerging technologies such as metasurfaces offer a platform by which these barriers can be overcome to develop the sensors needed to underpin this manufacturing transition. Here it is demonstrated that how a single metasurface can be used to deliver all the optical manipulations required to create a metasurface‐based confocal sensor with only the addition of a point source and point detector. By combining the optical functionality of both the illumination and the collection optics in this way the system is simplified and reduced in size significantly. While here how a metasurface can be used to reduce the number of elements needed to produce an ultra‐compact confocal sensor is demonstrated, this approach can be used to simplify a far wider range of instrumentation to greatly reduce their size and weight. [ABSTRACT FROM AUTHOR]

The integration of anionic Ti4L6 (L = embonate) cages and π-conjugated coordination cations into ordered structures can produce high-performance nonlinear optical (NLO) materials. More specifically, by employing Ti4L6 cages for assembly with mixed N,N-chelated and P,P-chelated type conjugated organic ligands and Ag+ ions, three cage-based structures have been synthesized and structurally characterized. Among them, an ion pair structure with strong π–π accumulation exhibits a significant third-order NLO response, and an excellent optical limiting effect has been experimentally verified. This work provides a promising material for NLO applications. [ABSTRACT FROM AUTHOR]

Chiral assemblies of plasmonic nanocrystals (NCs) are of immense interest due to their distinctive physicochemical characteristics and promising potential in future optoelectronic applications. Despite recent advances in the construction of chiral NC assemblies, most approaches have led to the formation of static irreversible structures with modest optical responses and limited configurational tunability. Herein, a way to prepare a thermally reconfigurable helical assembly of Au nanorods (AuNRs) with a strong chiroptical response is introduced by employing cholesteric liquid crystals (CLCs) as a chiral template. Circular dichroism (CD) spectroscopy and polarized optical microscopy are used to verify the strong chiroptical activity and dynamic optical tunability of chiral plasmonic film of AuNR–CLC composites and to unveil the interactions between constituents. For the system, chiral dopants are employed to induce strong helical procession along the hierarchical structure of the CLC template, resulting in a strong CD response, which can further be enhanced by increasing the amount of AuNRs. Furthermore, the thermotropic nature of the CLC template leads to the reversible on/off switching of the chiroptical responses of the system at a moderate temperature window with almost complete recovery of the original response, suggesting its feasibility as a promising material for chiral optoelectronic devices. [ABSTRACT FROM AUTHOR]

This paper explores the optical limiting (OL) characteristics of an input probe field within a closed-loop asymmetric coupled quantum well (ACQW) system. Our research reveals that the application of Terahertz (THz) coupling laser fields can induce the OL behavior within the THz domain in the ACQW. The study demonstrates that revers saturable absorption arises through cross-Kerr nonlinearity, contributing to the emergence of OL behavior. Additionally, it is shown that the self-defocusing is induced concurrently within the system, further enhancing nonlinear refractive OL effects. Furthermore, it is revealed that the properties of induced OL can be manipulated by adjusting the characteristics of the applied fields. The discovered outcomes hold potential utility in safeguarding sensors and detectors operating within the THz band. [ABSTRACT FROM AUTHOR]

Ultrafast lasers have significantly contributed to the advancement of research and technology; however, high‐intensity lasers bring potential risks to precision instruments and the human eye. Developing optical limiting (OL) devices capable of reasonably controlling laser energy to an acceptable energy level is imperative. Nevertheless, achieving both exceptional OL performance and broad‐spectrum laser intensity tunability proves highly challenging. In this work, the synthesis of a porphyrin‐based 2D polymer (Por‐2DP) using a template‐assisted self‐coupling polymerization, constructing a 2D framework through the carbon‐carbon single bond coupling of porphyrin monomer is presented. The resultant Por‐2DP demonstrates remarkable broadband nonlinear absorption performance, spanning the visible and near‐infrared spectral regions under an ultrafast pulse laser (35 fs) for the first time. OL thresholds at excitation wavelengths of 515, 800, and 1550 nm are determined to be 1.44, 0.48, and 0.54 mJ cm−2, respectively, surpassing reported 2D materials to date. Additionally, the Por‐2DP exhibits prominent photostability, enabling sustained operation under intense light conditions for a long time, thereby enhancing OL practical applicability. This study not only introduces a novel OL material and device but also promotes the application of innovative 2D organic polymers in NLO field. [ABSTRACT FROM AUTHOR]

Optical microscopy has undergone significant changes in recent decades due to the improved diffraction limit of optical resolution and the development of high-resolution imaging techniques referred to under the common name fluorescence nanoscopy. These techniques allow researchers to observe in detail biological structures and processes at a nanoscale level to reveal previously hidden features and answer basic biological questions. The advanced methods of fluorescent nanoscopy include STED (Stimulated Emission Depletion) Microscopy, STORM (STochastic Optical Reconstruction Microscopy), PALM (Photo-activated Localization Microscopy), TIRF (Total Internal Reflection Fluorescence) microscopy, SIM (Structured Illumination Microscopy), MINFLUX (Minimal Photon Fluxes) microscopy, PAINT (Points Accumulation for Imaging in Nanoscale Topography), and RESOLFT (REversible Saturable Optical Fluorescence Transitions) microscopy, and others. Most these methods make it possible to obtain 3D images of the objects under study. In this review, we consider the principles of these methods, their advantages and disadvantages, and their application in biological research. [ABSTRACT FROM AUTHOR]

Metallic nanoparticles have gained attention in technological fields, particularly photonics. The creation of silver/gold (Ag/Au) alloy NPs upon laser exposure of an assembly of these NPs was described. First, using the Nd: YAG pulsed laser ablation's second harmonic at the same average power and exposure time, Ag and Au NPs in distilled water were created individually. Next, the assembly of Ag and Au NP colloids was exposed again to the pulsed laser, and the effects were examined at different average powers and exposure times. Furthermore, Ag/Au alloy nanoparticles were synthesized with by raising the average power and exposure time. The absorption spectrum, average size, and shape of alloy NPs were obtained by using an ultraviolet-visible (UV–Vis) spectrophotometer and transmission electron microscope instrument. Ag/Au alloy NPs have been obtained in the limit of quantum dots (<10 nm). The optical band gap energies of the Ag/Au alloy colloidal solutions were assessed for different Ag/Au alloy NP concentrations and NP sizes as a function of the exposure time and average power. The experimental data showed a trend toward an increasing bandgap with decreasing nanoparticle size. The nonlinear optical characteristics of Ag/Au NPs were evaluated and measured by the Z-scan technique using high repetition rate (80 MHz), femtosecond (100 fs), and near-infrared (NIR) (750–850 nm) laser pulses. In open aperture (OA) Z-scan measurements, Ag, Au, and Ag/AuNPs present reverse saturation absorption (RSA) behavior, indicating a positive nonlinear absorption (NLA) coefficient. In the close-aperture (CA) measurements, the nonlinear refractive (NLR) indices (n2) of the Ag, Au, and Ag/Au NP samples were ascribed to the self-defocusing effect, indicating an effective negative nonlinearity for the nanoparticles. The NLA and NLR characteristics of the Ag/Au NPs colloids were found to be influenced by the incident power and excitation wavelength. The optical limiting (OL) effects of the Ag/Au alloy solution at various excitation wavelengths were studied. The OL effect of alloy NPs is greater than that of monometallic NPs. The Ag/Au bimetallic nanoparticles were found to be more suitable for optical-limiting applications. [ABSTRACT FROM AUTHOR]

Subwavelength gratings play a fundamental and pivotal role in numerous science and applications for wave manipulation, exhibiting distinctive features such as filtering, phase manipulation, and anti‐reflection. However, conventional fabrication methods for ultrasmall periodic structures are constrained by the fundamental optical diffraction limit, making it challenging to produce subwavelength gratings for optics. Here, a novel technique is demonstrated to build a reconfigurable subwavelength photorefractive grating (SPG) in a thin‐film lithium niobate on the platform of an optical microcavity. Such SPGs are optically induced through the photorefractive effect and the subwavelength features originate from the spatial phase modulations of the pump's standing wave. The resulting SPGs lead to the mode splitting of two counter‐propagating modes inside the microcavity, exhibiting an Electromagnetically Induced Transparency (EIT)‐like transmission spectrum. Moreover, the unique subwavelength characteristic of SPGs enables first‐order quasi‐phase‐matching for backward second‐harmonic generation, a long‐standing problem in nonlinear optics. Also, free‐space‐to‐chip vertical nonlinear frequency conversion can be achieved in a similar manner. These results provide a flexible approach toward fabricating subwavelength gratings, which holds significant potential in various applications such as nonlinear frequency conversion, optical communication, sensing, and quantum technologies. [ABSTRACT FROM AUTHOR]

Titanium and its alloys are known to allow the straightforward laser‐based manufacturing of ordered surface nanostructures, so‐called high spatial frequency laser‐induced periodic surface structures (HSFL). These structures exhibit sub‐100 nm spatial periods – far below the optical diffraction limit. The resulting surface functionalities are usually enabled by both, topographic and chemical alterations of the nanostructured surfaces. For exploring these effects, multi‐method characterizations were performed here for HSFL processed on Ti–6Al–4V alloy upon irradiation with near‐infrared ps‐laser pulses (1030 nm, ≈1 ps pulse duration, 1–400 kHz) under different laser scan processing conditions, i.e., by systematically varying the pulse repetition frequency and the number of laser irradiation passes. The sample characterization involved morphological and topographical investigations by scanning electron microscopy (SEM), atomic force microscopy (AFM), tactile stylus profilometry, as well as near‐surface chemical analyses hard X‐ray photoelectron spectroscopy (HAXPES) and depth‐profiling time‐of‐flight secondary ion mass spectrometry (ToF‐SIMS). This provides a quantification of the laser ablation depth, the geometrical HSFL characteristics and enables new insights into the depth extent and the nature of the non‐ablative laser‐induced near‐surface oxidation accompanying these nanostructures. This allows to answer the questions how the processing of HSFL can be industrially scaled up, and whether the latter is limited by heat‐accumulation effects. [ABSTRACT FROM AUTHOR]

Disordered and correlated disordered photonic materials have emerged in the past few decades and have been rapidly proposed as a complementary alternative to ordered photonics. These materials have thrived in the field of photonics, revealing the considerable impact of disorder with and without structural correlations on the scattering, transport, and localization of light in matter. Scanning near-field optical microscopy (SNOM) has proven to be a fundamental tool for the study of the interaction between light and matter at the nanoscale in such systems, allowing for the investigation of optical properties and local electromagnetic fields with extremely high spatial resolution, surpassing the diffraction limit of conventional optical microscopy. In this review, the most important and recent advances obtained for disordered and correlated disordered luminescent structures by means of the aperture SNOM technique are addressed, showing how it allows the tailoring of local density of states (LDOS), as well as providing access to statistical analysis for multi-resonance disordered and hyperuniform disordered structures at telecom wavelengths. [ABSTRACT FROM AUTHOR]

Metal halide perovskites (MHPs) have attracted increasing attention in various optoelectronic devices due to their exceptional optical and electrical properties. The high precision patterning of MHPs is crucial adjective for device fabrication, while it is severely hindered by the active and sensitive chemistry of MHPs. In this work, high resolution and tunable nanostructuring of 2D MHP films are achieved by ultrafast laser direct writing (ULDW). The feature size of the created structure is down to 47 nm (λ/21), which is far beyond the diffraction limit of the optical system. The study proves the critical influence of the thermodynamic properties of materials on structure morphologies and establish a new mechanism of molten phase self‐evolution (MPSE) for the formation of super‐solution convex structures, which provides a new understanding for ultrafast laser‐matter interaction and high‐resolution patterning with ULDW. Different structure morphologies bring tunable optical properties. The applications are demonstrated in multimode information storage and encryption. The findings open new approaches to achieve hyperfine multi‐morphological structures on MHPs, which can boost many MHPs integration applications in nanophotonics, on‐chip electronics, and information encryption. [ABSTRACT FROM AUTHOR]

In this study, electrospun cobalt (Co)- and iron (Fe)-doped nickel oxide (NiO) nanofilled polyvinylpyrrolidone (PVP) composite nanofibers were produced, and their linear and nonlinear optical and optical limiting properties were investigated. Three distinct average particle sizes (61, 110, and 150 nm) of Co- and Fe-doped NiO nanoparticles were produced using the coprecipitation method. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD) techniques were used to analyze the morphology and structure of particles. Composite nanofibers were found to be homogeneous and continuous, with average diameters ranging from 177 to 314 nm. It was found that different particle sizes of Co- and Fe-doped NiO nanoparticles and aggregations in nanofibers did not have a significant effect on the results. The Fe-doped structure mostly contained defect states and showed the weakest fluorescence emission among the other composite nanofibers. These behaviors indicate a further charge transfer mechanism via defect states, with multiphoton absorption favoring nonlinear absorption. Open aperture Z-scan experiments were carried out at 532 nm with a 4-ns pulsed laser to observe the nonlinear optical features of nanocomposite fibers. It was observed that all of the composite nanofibers exhibited a nonlinear absorption (NA) feature, which weakened with an increase in input intensity. The Fe-doped structure, characterized by more defect states, demonstrated the strongest NA behavior. All of the composite nanofibers displayed a strong optical limiting behavior within the range of 1.35 × 10-5 and 1.92 × 10-5 J/cm². Given the strong NA and robust optical confinement behavior of Fe-doped NiO nanoparticles, composite nanofibers have emerged as promising candidates for optoelectronic applications in the visible spectral region. [ABSTRACT FROM AUTHOR]

Concatenated backward ray mapping is an alternative for ray tracing in 2D. It is based on the phase-space description of an optical system. Phase space is the set of position and direction coordinates of light rays intersecting a surface. The original algorithm (Filosa, ten Thije Boonkkamp and IJzerman in J Math Ind 11(1):4, 2021) is limited to optical systems consisting of only straight surfaces; we generalize it to accommodate curved surfaces. The algorithm is applied to a standard optical system, the compound parabolic concentrator. We compare the accuracy and speed of the generalized algorithm, the original algorithm and Monte Carlo ray tracing. The results show that the generalized algorithm outperforms both other methods. [ABSTRACT FROM AUTHOR]

Two Curcumin (Cur) based mixed ligand complexes of Nickel have been investigated for their optical nonlinearity (NLO). Physicochemical characterization of two nickel precursors and their interaction with curcumin produced two molecules, namely Ni(C3S5)(Cur).2H2O (abbreviated as NiThCur) and NiCl(Cur)(PPh3) (abbreviated as NiTppCur). Additionally the Conceptual‐Density‐Functional‐Theory (CDFT) studies were performed. CDFT‐based optimization parameters of both molecules are theoretically interpreted. HOMO‐LUMO energy gap of NiThCur and NiTppCur were calculated 1.474 eV and 2.744 eV respectively. Both molecules demonstrated good NLO activities, studied by a Z‐scan approach and additionally with a Differential Four wave Mixing (DFWM) technique. Preliminarily investigations showed that the molecules can be potential optical limiters (OL). These studies divulge the exhibition of a 3‐photon absorption (3PA) mechanism by the synthesized molecules. NLO absorption 3PA coefficient (γ) value of 1.34×10−24 m3/W2, third‐order optical susceptibility (χ(3)) value of 1.543×10−11 esu, and the figure of merit 6.64×10−14 esu was observed for the NiThCur complex and γ=3.61×10−24 m3/W2, χ(3)=1.521×10−11 esu, and FoM=5.61×10−14 esu for NiTppCur with Z‐scan (γ and χ(3)) and DFWM methods, respectively. Normalized transmittance (NT) exhibited a decrease to 78.5 % from 100 % in NiThCur and to 69.5 % in NiTppCur. Optical limiting calculations are also presented. [ABSTRACT FROM AUTHOR]

The structural dependence of nonlinear optical properties associated with ADP-doped PVA/PVP polymer composites is discussed in this work. Polymer composites are fabricated using the solution casting method. X-ray diffraction (XRD) was used to perform structural analysis on these samples whose average crystallite size increases with an increase in dopant concentration. Results from UV–Vis–NIR spectra show that the samples are transparent in the IR region. The Z-scan technique was established by following the method described by Sheik-Bahae et al. The shape of the open aperture plot suggests that the samples exhibit two-photon absorption. The NLO properties such as nonlinear absorption coefficient (β) , two-photon absorption cross-section ( σ 2) and the imaginary part of third-order nonlinear susceptibility (χ (3)) were investigated at 1064 nm and these values were found to be in the order of ∼ 1 0 − 7 W/cm, ∼ 1 0 − 2 0 cm4/GW and ∼ 1 0 − 1 4 esu, respectively. The open aperture Z-scan method yielded optical limiting data, from which the optical limiting threshold was calculated to be in the order of ∼ 1 0 1 3 W/m2. Functional data analysis uses a suitable basis representation to assess the functional correlation between global and local variables. [ABSTRACT FROM AUTHOR]

External‐field controllable light‐guiding structures are critical in the field of optical circuits and optical integration, and many well‐designed solid‐state waveguides have good performance but are weakly controllable. Although there have been attempts at liquid light guiding, liquid‐filled waveguides cannot completely break the constraints of the solid structure, and in liquid crystal (LC), the smaller tuning angle of the optical soliton limits its further application. So designing a soft tunable light‐guiding structure becomes an urgent but challenging task. In this work, a novel electrically switchable light‐guiding structure with LC programmable wall defect is designed and verified. Wide‐angle recyclable switching of light guiding under an electric field and optical erasure and rewriting of the structure are realized, unleashing the potential of soft‐matter defect structures, and paving the way for soft optical devices and optoelectronic integration. [ABSTRACT FROM AUTHOR]

The compelling demand for laser protection both for civil and defense use calls for new‐generation nonlinear optical materials. Chemical vapor deposition (CVD) techniques provide extra tricks to modulate crystal optical nonlinearity through fractal growth. The synthesized 2D NbSe2 and its fractal structures exhibit giant, broadband laser attenuation behaviors extending into the near Infrared (NIR) range. Particularly, the optical limiting performance generally correlates with the fractal dimension, where Fractal NbSe2 demonstrates enhanced third‐order optical nonlinearity at a huge nonlinear absorption coefficient of 9.7 × 10−4 m W−1 and an ultralow starting threshold of 5 mJ cm−2 at 532 nm. Various techniques include femtosecond spectroscopy, Density functional theory (DFT) calculation and Kelvin probe force microscopy disclose the origin of the strong nonlinearity of the 2D NbSe2 crystals, and suggest the formation of edge states and overall faster carrier dynamics, larger surface contact potential difference NbSe2 fractals contribute to their even augmented nonlinear responses. Fractal engineering thus opens new avenues to fabricate highly efficient laser protection materials, and the blocking of intense beam (a large attenuation factor over 13.3 dB at 532 nm) while allowing transmission of weak one (a high linear optical transmittance over 80%) fulfills the much desired "smart" defense. [ABSTRACT FROM AUTHOR]

The impact of photon recycling (PR) and of luminescent coupling (LC) on the photovoltaic performance of all‐perovskite tandem solar cells is analyzed by the means of optical and full opto‐electronic device simulation. Optical processes are assessed using a comprehensive Green function formalism that considers wave optical effects also in emission. Starting from a consistent fit of experimental sub‐cell and tandem characteristics, the effects of re‐absorption are propagated from the optical limit to a situation with consideration of realistic charge transport across the entire tandem device. This also provides insight into the origin of performance losses due to sub‐cell and interconnection quality. [ABSTRACT FROM AUTHOR]

Wavefront Coding (WFC) is an innovative technique aimed at extending the depth of focus (DOF) of optics imaging systems. In digital imaging systems, super-resolution digital reconstruction close to the diffraction limit of optical systems has always been a hot research topic. With the design of a point spread function (PSF) generated by a suitably phase mask, WFC could also be used in super-resolution image reconstruction. In this paper, we use a deep learning network combined with WFC as a general framework for images reconstruction, and verify its possibility and effectiveness. Considering the blur and additive noise simultaneously, we proposed three super-resolution image reconstruction procedures utilizing convolutional neural networks (CNN) based on mean square error (MSE) loss, conditional Generative Adversarial Networks (CGAN), and Swin Transformer Networks (SwinIR) based on mean absolute error (MAE) loss. We verified their effectiveness by simulation experiments. A comparison of experimental results shows that the SwinIR deep residual network structure based on MAE loss optimization criteria can generate more realistic super-resolution images with more details. In addition, we used a WFC camera to obtain a resolution test target and real scene images for experiments. Using the resolution test target, we demonstrated that the spatial resolution could be improved from 55.6 lp/mm to 124 lp/mm by the proposed super-resolution reconstruction procedure. The reconstruction results show that the proposed deep learning network model is superior to the traditional method in reconstructing high-frequency details and effectively suppressing noise, with the resolution approaching the diffraction limit. [ABSTRACT FROM AUTHOR]

Tris(2,4,6‐trichlorophenyl)methyl (TTM) group has been widely used for constructing organic radicals, but the poor optical stabilities limit the application prospects of the TTM radicals. In this work, the rigid B‐ and N‐embedded dioxygen‐bridged (BO and NO) units were attached to the TTM skeleton as the strong electron‐withdrawing and electron‐donating groups, respectively. The rigidity and strong electronic effect of the BO and NO units contribute to the high chemical and optical stability of BO‐TTM and NO‐TTM radicals. Notably, NO‐TTM exhibits near‐infrared emission at 830 nm with a narrow full width at half maximum (FWHM) of 55 nm (100 meV), while BO‐TTM shows blue‐shifted luminescence at 635 nm and a narrower FWHM of merely 43 nm (130 meV). This study has developed a methodology to produce highly efficient and enduring luminescent radicals, which could tune emission properties such as wavelength and FWHM. [ABSTRACT FROM AUTHOR]