Optical Materials最新文献

The growing interest in carbon dots (CDs) arises from their diverse applications and unique properties. This study addresses challenges in CDs for photodetector (PD) applications, specifically surface defects and trap states hindering efficient charge transport. CDs/P3HT composites were prepared to overcome these issues by incorporating CDs in a poly(3-hexylthiophene) (P3HT) matrix. Broad absorption in spectroscopic characterization revealed its utility in fabricating a broadband PD. The CDs/P3HT PD displays a remarkable broadband photoresponse, spanning both UV and visible regions. The CDs and P3HT are effectively combined via non-covalent π-π interactions constituted by their conjugated systems. The π-π interaction increases electron delocalization and facilitates efficient charge transfer due to band alignment at the junction interface. Hence, fabricated CDs/P3HT PD demonstrated enhanced photocurrent compared to pure CDs, exhibiting high responsivity of 6.12 × 10⁻³ AW⁻¹ and detectivity of 0.69 × 10⁹ Jones. This study highlights the potential of CD/P3HT composites for broadband photodetector applications with enhanced photoelectric conversion.

Heterogeneous semiconductor photocatalysis has attracted researcher's attention in wastewater treatment owing to the improved surface area, optical properties, and charge transfer rate for boosted degradation of organic pollutants. Thus, the g-C₃N₄/Ag/TiO₂ was prepared following a hydrothermal route for the degradation of azo dye tartrazine (TA) used as a food colourant under solar light. Before application, the composite and pristine materials were interrogated for physicochemical and structural properties using SEM, TEM, EDS, XPS, XRD, UV–vis DRS, PL, BET, Raman, and FTIR spectroscopy. The PL and electrochemical analysis revealed that the CNAT composite had a high charge transfer rate that was coupled with low charge carrier complexation. The degradation efficiency of 91 % was realized in 180 min and the rate of pseudo-first-order kinetics of 0.01143 min⁻¹ was obtained. The CNAT catalyst also displayed high removal efficiency towards a cocktail of naproxen (NPX) and TA. The improved removal efficiencies stem from increased visible usage, reduced charge carrier compounding, and formation of Z-scheme heterojunction with high redox capabilities. The total organic carbon removal reached 95 % while CNAT showed high convincing stability even after four cycles. Given the above results, the hydrothermally prepared composite catalyst can be extended to other organic pollutants such as pharmaceuticals, pesticides, and reduction of inorganics.

This work shows the synthesis and characterization of the Zn_2-xGeO₄-GeO₂:(x)Mn²⁺ (x = 0.10, 0.25, and 0.50 at.%) films using the Ultrasonic Spray Pyrolysis (USP) technique. These films were deposited at 500 °C and heat treated at 800 °C for 13 h. X-ray diffraction (XRD) measurements showed the rhombohedral and hexagonal phases of Zn_2-xGeO₄ (78.8 %) and GeO₂ (21.2 %), respectively. SEM micrographs exhibited the surface morphology of these films. The STEM and HAADF show Ge, Zn, and O atomic layers. In addition, XPS was carried out to observe the oxidation states of Mn²⁺ (75.4 %) and Mn³⁺ (24.6 %) for the films doped with Mn ions (0.10 at.%). Incorporating manganese ions into the Zn_2-xGeO₄-GeO₂ host lattice generated an extremely green emission, exciting at 250 nm. The photoluminescence and persistence luminescence properties were studied in accordance with the manganese doping concentration. For photoluminescence, it was found that the optimal doping percentage was 0.25 at.%, and for persistence luminescence, it was 0.10 at.% Mn with λ_ex = 250 nm. Quantum efficiency measurements gave a result of 100 %. In addition, preliminary CL measurements were exhibited.

In this paper, we propose a new and efficient ferroelectric nanostructure metal oxide lithium niobate [(Li_1.075Nb_0.625Ti_0.45O₃), (LNTO)] solid film as a saturable absorber (SA) for modulating passive Q-switched erbium-doped fiber laser (EDFL). The SA is fabricated as a nanocomposite solid film by the drop-casting process in which the LNTO is planted within polyvinylidene fluoride-trifluoroethylene [P(VDF-TrFE)] as host copolymer. The optical and physical characteristics of the solid film are experimentally established. The SA is incorporated within the cavity of EDFL to examine its capability for producing multi-wavelength laser. The experimental results proved that a multi-wavelength laser is produced, where stable four lines with central wavelengths at 1529.5, 1530.5, 1531.5, and 1532 nm are observed on the laser spectrum at 157 mW pumped power. Furthermore, at maximum available pumped power (157 mW), laser pulses are running with a rate of 178 kHz and pulse width of 2.64 μs. The output power of 3.7 mW is attained at pumped power of 157 mW. The result proved that the LNTO-SA could be a potential candidate for generating multi-wavelength passive Q-switched fiber laser pulses.

The current study delves into exploring the linear and nonlinear optical properties of (E)-3-(4-methylthiazole-5-yl)-1-(3-nitrophenyl)prop-2-en-1-one (MNP) through a combined approach of theoretical predictions and experimental observations. By employing single crystal X-ray diffraction analysis, the MNP's crystal structure has been confirmed, establishing its categorization as triclinic with the P-1 space group. The grown crystal was characterized through UV–Vis studies, photoluminescence studies, and thermal analysis. The absorption spectrum of MNP was examined using UV–Vis analysis in various solvents, revealing a strong absorption peak between 335 and 357 nm, suggesting its suitability for UV-based optoelectronic applications also the MNP exhibits good nonlinear optical (NLO) responses, including α_CT, β_CT, and γ_CT values, across different solvent environments. The examination of MNP's third-order nonlinear optical properties and its optical limiting behavior was conducted using the Z-scan technique with a continuous wave (CW) laser at 532 nm. The results revealed substantial χ⁽³⁾ values of 3.01×10⁻⁶ esu, and an optical limiting threshold observed at 4.213×10³ Wcm⁻². The experimental results were corroborated by theoretical calculations derived from density functional theory (DFT). DFT calculations were used to explore MNP's electronic structure and charge distribution, utilizing FMO, MEP, and NBO analysis. Furthermore, the time-dependent Hartree-Fock (TDHF) method was employed to compute the static and dynamic linear polarizability (α) along with the first and second hyperpolarizability (β and γ) of MNP. Notably, the first hyperpolarizability exceeded the urea standard by 91.03 times at a wavelength of 532 nm, and the computed second-order hyperpolarizability value of 0.42×10⁻³²esu. closely matches the experimental observations in DMSO solvent (0.25×10⁻³¹esu). Overall, the findings of these studies indicate that the synthesized chalcone derivative material holds potential for optoelectronic applications.

This work presents the investigation of the photoconductivity effect in undoped and doped Pb_0.5Sn_0.5Te epitaxial films, with bismuth (Bi) atoms, at temperatures of 80 and 300 K. The results indicate that the samples show negative photoconductivity effect (NPC) and persistent photoconductivity (PPC). A detailed study was performed on Pb_0.5Sn_0.5Te sample doped with 0.15 % Bi, which presented higher photoconductivity amplitude than the other samples, by performing Hall effect and photoconductivity measurements in the temperature range of 80–300 K under dark and illuminated conditions. Using Arrhenius model, trap activation energy was extracted and compared with energies found in literature. From the Hall measurement we found that the NPC effect observed is due to a decrease in the mobility when the sample is illuminated while the carrier concentrations are nearly unaltered. It was also found that Pb_0.5Sn_0.5Te:Bi presented photoconductivity response for a wide range of wavelengths, indicating that it is potentially interesting for application in optic sensor devices.

SiO₂–B₂O₃-GdF₃-CaO-Bi₂O₃ doped glasses containing Er³⁺/Yb³⁺ ions at varying concentrations were successfully synthesized using a high-temperature melting method. The glass samples' physicochemical properties and amorphous structure were characterized through density, XRD, XPS, FT-IR, and Raman analyses. Thermal expansion coefficient testing indicated good thermal stability of the glass system. Increasing the Yb³⁺ doping concentration enhanced near-infrared luminescence at 1.53 μm, with maximum luminescence intensity at approximately 3.2 mol% doping concentration. The energy transfer mechanism of Er³⁺/Yb³⁺ doped SiO₂–B₂O₃-GdF₃-CaO-Bi₂O₃ glass was elucidated through fluorescence spectrum analysis, revealing J-O parameters Ω₂ = 11.2 × 10⁻²⁰ cm², Ω₄ = 8.9 × 10⁻²⁰ cm², and Ω₆ = 9.59 × 10⁻²⁰ cm². Calculations for absorption cross-section, cross-section of emission, and gain curve additionally reinforced the glass's capability for laser uses.

This study focuses on the synthesis of Sm³⁺ and Eu³⁺ rare earth ions doped zinc boro-phosphate glasses and their physical, optical and spectral characterization. Photoluminescence was carried out through both steady-state and time-domain luminescence measurements. The glasses were prepared via the melt quenching technique, and they exhibit impressive mechanical strength and transparency. Judd-Ofelt analysis of the near-infrared absorption spectra revealed parameters Ω₂, Ω₄, and Ω₆, indicating low covalency and reduced site asymmetry for the rare earth ions compared to those in silicate-based glasses. When excited with violet light, the Sm³⁺-doped samples emitted bright orange luminescence, resulting from radiative relaxation from the ⁴G₅_/₂ state to lower energy levels. The calculated branching ratios correspond well with the observed emission peak ratios. However, increasing the Sm³⁺ ion concentration resulted in reduced luminescence intensity and shorter fluorescence lifetimes, due to cross-relaxation effects. In the Sm³⁺/Eu³⁺ co-doped glasses, energy transfer from Sm³⁺ to Eu³⁺ ions was detected upon selective excitation of Sm³⁺ ions. This energy transfer efficiency was found to increase with higher concentrations of Eu³⁺ ions.