We employ spatially tailored laser shapes to impress metastable photoluminescence pattern on mixed-halide perovskites thin-films. A novel two-dimensional deformable phase plate spatial laser shaper is integrated into a microscopy setup to investigate controllable patterning of light-induced halide segregation. Different spatial beam profiles demonstrate the controllability of the patterning method. The imprinted profiles show self-erasure within minutes, demonstrating metastability due to reversible remixing of segregated halides. Imprinted shapes are observed by spectrally separated photoluminescence imaging of mixed halide and iodide-rich phases in perovskite thin-films.
To meet the rapidly growing demands for flexible diffractive optical elements (DOEs) fabrication, this paper presents a simple and precise fabrication method based on polymer molds and PDMS casting. Compared with other similar fabrication methods, the proposed method achieves a minimum feature size of 1μm, which is 4-fold smaller than the 4μm feature size reported in the most comparable method, and does not require mold surface treatment or complex equipment. The proposed fabrication method also demonstrates excellent repeatability, maintaining stable microstructure quality with lateral width errors within 9.2% and vertical height errors within 3.73%. The fabricated flexible beam shaping DOE shows reliable strain properties, enabling tunable beam shaping under horizontal and longitudinal mechanical strains of 0-60%, with CV (coefficient of variation) variation below 12% and diffractive efficiency variation below 4.5%. Furthermore, the fabricated DOE exhibits outstanding fatigue resistance properties. This method offers an economically efficient and practical solution for the fabrication of flexible DOEs.
This study utilizes the synergistic co-doping of Ce and Bi to enhance the magneto-optic effect of LuIG crystals, while Ca2+ is incorporated via charge compensation to improve the optical transmittance of Ce,Bi,Ca:LuIG crystals. Using the top-seeded solution growth (TSSG) method and a lead-free Bi2O3-Fe2O3 self-flux system, a series of centimeter-sized Ce,Bi,Ca:LuIG single crystals were successfully fabricated. The crystals possess high crystalline quality with minor compositional fluctuation and homogeneous distribution of Ce3+ and Bi3+ ions. Faraday rotation measurements confirm that the cooperative effect of Bi3+ and Ce3+ significantly boosts the magneto-optic performance. In particular, the crystal with the highest doping concentrations of Bi3+ and Ce3+, Ce0.12Bi0.50Gd0.05Lu2.29Ca0.04Fe4.82Ga0.18O12, exhibits a specific Faraday rotation of -615.2 deg cm-1 at 1550 nm, which is about 3.4 times that of a YIG crystal. Overall, Ce,Bi,Ca:LuIG crystals with high optical transmittance and strong magneto-optic response are highly promising for use in magneto-optic isolators operating at 1550 nm.
The waste polyester textile-based activated carbon (WPT-AC) was prepared by ZnCl2 activation method with waste polyester as raw material, and the waste polyester textile-based activated carbon loaded graphite phase carbon nitride (WPT-AC/g-C3N4) was prepared by direct thermal polymerization method with the prepared WPT-AC and melamine as raw materials. The crystal, group, morphology and photochemical properties of WPT-AC/g-C3N4 photocatalyst were characterized by X-ray diffraction (XRD), infrared spectroscopy (FTIR), transmission electron microscopy (TEM), UV-visible diffuse reflection spectroscopy (UV-vis DRS), transient fluorescence spectroscopy (PL) and electrochemical AC impedance spectroscopy (EIS). At the same time, the dark adsorption and photocatalytic properties of the photocatalyst WPT-AC/g-C3N4 were studied with methylene blue (MB) as the simulated dye, and the stability of the photocatalyst was also studied. Results demonstrate that optimal WPT-AC doping prevents the layer stacking of g-C3N4, maximizing the specific surface area at 48.7 m2/g to expose abundant active sites. Concurrently, the overlapping π-π* conjugated system mitigates the recombination of photogenerated carriers, thereby boosting the overall photocatalytic performance. When the visible light was irradiated for 2 h, the dark adsorption capacity of 0.1 g 5% (mass fraction) WPT-AC/g-C3N4 photocatalyst to 100 mL MB with the mass concentration of 35 mg/L was 13.51 mg/g, and the photocatalytic degradation rate reached 98%. Furthermore, the WPT-AC/g-C3N4 catalyst exhibited excellent stability, maintaining a degradation rate of over 90% for MB after 5 recycling cycles. Trapping experiments revealed that superoxide radicals (•O2-) and holes (h+) are the key active species during the photocatalytic process.
