Optical and Quantum Electronics最新文献

In thicker polymer active layers charge collection efficiency suffers due to low carrier mobility and increased recombination losses. In thin absorber polymer solar cell to increase absorption, light-trapping techniques and plasmonic structures are essential. This study investigates the effect of shell thickness on the photocurrent density of a poly(3-hexylthiophene): phenyl-C61- butyric acid methyl ester (P₃HT:PCBM) polymer based solar cell incorporating core–shell nanoparticles with configurations of Au–Ag and Ag-Au core–shell nanoparticles. Through a series of simulation, the photocurrent density was calculated as a function of shell thickness. The results demonstrate that, for both nanoparticle configurations, the photocurrent density generally increases with shell thickness, reaching an optimal point before stabilizing or slightly decreasing. Additionally, the effects of dielectric shells made of SiO₂ and Al₂O₃ on its performance parameters were analyzed. The study also found that the photocurrent decreases with increasing shell thickness for both SiO₂ and Al₂O₃ shells, with a more pronounced decrease for SiO₂ due to its smaller refractive index and greater change in shorter wavelengths. The photocurrent density of 13.74 mA/cm² is achieved for a cell with a thickness of 80 nm without nanoparticles. This value increases to 16.62 mA/cm² for a cell incorporating Ag nanoparticles and reaches 19.3 mA/cm² for a cell with Au–Ag core–shell nanoparticles at the optimal shell thickness. The power conversion efficiency of the polymer solar cell increases from 7.02% without nanoparticles to 8.67% with Ag, 8.45% with Au, and reaches the highest value of 10.26% with Au–Ag core–shell nanoparticles, highlighting the superior performance of the core–shell configuration. This superior performance is attributed to the enhanced plasmonic effects of the Au–Ag combination, which facilitates better light trapping and absorption. These findings underscore the importance of optimizing shell thickness and material composition in core–shell nanoparticles and dielectric shells to maximize the efficiency of photovoltaic cells.

In this paper, a hollow-core anti-resonant optical fibre containing a semi-elliptical nested tube is proposed, which has the characteristics of single-polarization, large bandwidth, single-mode and low confinement loss. By optimizing the structural design, the polarization extinction ratio (PER) of the fiber reaches 21,0183 at a wavelength of 1.55 (mu)m, and the y-polarized fundamental mode loss is only 0.00086 dB/m. By changing the material and thickness of the semi-ellipsoidal nested tube, a large bandwidth of 280 nm was achieved in the wavelength range of 1.51(-)1.78 (mu)m, with loss limited to less than 0.001 dB/m within the bandwidth range. The PER and higher-order mode extinction ratio of 4870, 1487, respectively. The loss remains below 0.01 dB/m when the bending radius exceeds 4.5 cm. Therefore, it is expected that this optical fiber can be used in optical devices such as fiber optic sensors, fiber optic lasers and fiber optic gyroscopes.

This paper investigates the third harmonic generation (THG) process due to Stimulated Raman Scattering (SRS) in a magnetized plasma using a Hermite cosh Gaussian laser beam (HchG). The unique intensity profile of the HchG laser beam interacts with the plasma which leads to the generation of plasma waves and sideband electromagnetic waves i.e. stokes and Anti-stokes waves. This interaction leads to density perturbation inside the plasma, which couples with the laser wave, resulting in THG. A nonlinear wave equation, along with the equation of motion for plasma electrons, is employed to derive the dispersion relation and analyze the growth rate of the SRS instability. The study incorporates the effects of a static magnetic field, focusing on cold and underdense plasma conditions. The results demonstrate that the HchG beam’s spatial profile enhances the efficiency of THG and significantly impacts the growth rate and characteristics of SRS, suggesting that modulating laser beam profiles can effectively control plasma dynamics.

The simple hot-water-vapor (HWV) method was used to make the copper oxide nanostructures on Cu sheets for this study. The effects of oxidation times of 8, 16, and 24 h were investigated for use in solar cells. The samples were characterized using FESEM, EDX, XRD, Raman, and DRS measurements. It is found that with increasing the synthesis time duration: (1) the FESEM images showed a combination of cubic and nano-leaves gradually turned into compact nano-leaves; (2) EDX, XRD, and Raman analyses on the samples showed that the layers that were grown got closer to the CuO phase’s elemental ratio, and the crystallite size (D) grew from 17.55 to 34.66 nm; (3) It was found that the CuO phase-related band gap decreased from 1.62 to 1.43 eV as the crystallinity and phase purity of the samples improved, which could be a beneficial property for solar cell applications.

First-principles DFT calculations on Sr₂TbXO₆ (X = Bi, Sb) double perovskites were performed using the WIEN2K code, with PBE-GGA for electronic structure optimization and the LAPW method for valence and core electrons. Structural optimization of Sr₂TbXO₆ (X = Bi, Sb) using PBE-GGA revealed the most stable structure, with the Birch-Murnaghan EOS used to calculate key ground state parameters. Substituting Bi with Sb reduced the lattice parameter, and phonon dispersion confirmed dynamic stability, highlighting potential for thermoelectric applications. The elastic properties of Sr₂TbXO₆ (X = Bi, Sb) confirm mechanical stability and brittle behavior, with Sr₂TbSbO₆ showing higher stiffness due to a greater Young's modulus. Both compounds exhibit elastic anisotropy and ionic bonding, as indicated by positive Cauchy pressures. The electronic band structures of Sr₂TbBiO₆ and Sr₂TbSbO₆ exhibit similar band gaps in both spin configurations, indicating comparable semiconducting behavior. However, flat states near the Fermi level in the spin-down channel, due to localized 4f electrons from Tb, enhance electron–electron interactions and suggest potential applications in spintronics and correlated electron systems. The magnetic moments of Sr₂TbBiO₆ and Sr₂TbSbO₆ are dominated by Tb, contributing 6.06 μB and 5.85 μB, respectively, with minimal contributions from other atoms and interstitial regions. Both compounds have total magnetic moments of 6.00 μB. Sr₂TbBiO₆ and Sr₂TbSbO₆ exhibit maximum thermal expansion at 0 GPa, decreasing with increasing pressure as atomic mobility becomes restricted. Heat capacity and volume increase with pressure and temperature, while the Debye temperature decreases due to softer phonon modes at higher temperatures.

As perovskite solar cell (PSC) technology nears commercialization, concerns about lead content and biodegradability remain significant. Lead-free double perovskite materials, like Cs₂AgBiBr₆, have garnered attention for their reduced toxicity and improved stability. Cs₂AgBiBr₆ perovskites, in particular, show promise for photovoltaic applications due to these benefits. In this paper, we propose the design and conduct numerical simulations of a double perovskite solar cell based on Cs₂AgBiBr₆, aiming to address the need for safer and more stable alternatives in PSC technology. The initial tested cell, derived from experimental work, features a hydrogenated Cs₂AgBiBr₆ layer with an unprecedented low bandgap of 1.64 eV. The cell structure, FTO/TiO₂/Cs₂AgBiBr₆/Spiro-OMeTAD/Metal back contact (Flat Band, φ_m = 5.18 eV), achieved a maximum power conversion efficiency (PCE) of 26.61%. It also recorded an open-circuit voltage (V_oc) of 1.58 V, a short-circuit current density (J_sc) of 20.98 mA/cm², and a fill factor (FF) of 80.10% at an optimal absorber layer thickness of 800 nm. Both bulk and interface defects were analyzed, revealing that optimizing the interface between the HTL and perovskite is more critical than the ETL/perovskite interface due to higher recombination current at the HTL/perovskite interface. Overall, the simulation results from this study provide valuable insights for designing environmentally friendly perovskite solar cells.

In this paper, we analyze and review the performance of refractive index (RI) sensors for detecting human blood groups (BGs). Additionally, we introduce the standard deviation (SD) as a means to identify the optimal highest resolution sensor. We design and simulate the behavior of 14 different nano-RI sensors based on Metal-Insulator-Metal (MIM) plasmonic waveguides using the FDTD method. Previously, it was believed that the most effective sensor for sensing BGs would be the one with the highest sensitivity. However, our research has revealed otherwise, showing that the best sensor is not necessarily the one with the highest sensitivity. Significant observations indicate that the sensor with the highest sensitivity does not necessarily provide the best blood type resolution. Instead, it is the sensor that can generate the maximum spectral distance between the resonance peaks. Our conclusion was reached through an analysis of the spectrum of blood groups A, O, and B (BGAOB). To evaluate the resolving power between different BG resonance peaks, we introduced SD parameter as a key metric for assessing blood type differentiation, clarifying that a larger SD correlates with improved resolution. By comparing SD, we identified the sensor that creates the greatest spectral distance between the peaks. This finding is highly valuable and effective in optimizing the design and comparison of BG sensors, ultimately resulting in sensors with enhanced sensing capabilities. With the proposed sensor configurations and the defined mathematical model, we achieved optimal performance in BG sensing. This nanoscale structure and high-resolution approach offer a promising option for designing non-invasive sensors on a single chip.

Quantum dots composed of lead Sulphide (PbS) are garnering significant interest for their potential to enhance the efficiency of solar cells. These materials exhibit outstanding qualities such as high quantum yield, adjustable band gap, cost-effectiveness, improved stability, and easy tunable electronic properties. Our research achieved an impressive energy conversion efficiency of 23.29% by replacing a suitable electron transport layer (ETL) in the architecture ITO/ETL/PbS-TBAI/MoO₃/Au. Advanced computational techniques, specifically SCAPS-1D, have been utilized to theoretically study the solar cell, allowing for detailed exploration of device performance before fabrication. Computational modelling is crucial in predicting key parameters such as efficiency, short circuit current density, open circuit voltage, and fill factor, enabling us to optimize the design iteratively and efficiently. Furthermore, we examined energy band alignment, current density–voltage characteristics, quantum efficiency curves, and the composition and arrangement of materials to refine device architecture. This approach not only enhances our understanding of the underlying physics but also accelerates the development of high-performance solar cells based on PbS quantum dots.

The Hirota bilinear method was utilized to study a (3+1)-dimensional soliton equation, and we achieved success in obtaining a variety of solutions to the equation. Successfully yielding various solutions, such as lump solutions, rogue wave solutions, and interaction solutions. The first step in research is to transform the orginal equation into Hirota bilinear form. Through the symbolic calculation and the Cole-Hopf transformation, we obtain the solution of the original equation. Especially, we introduced vectors as tools to get the rational solutions of the equation. We make plots according to select different values of parameters, and the plots of various forms of solutions are dynamically analyzed to understand their physical significance. For the selection of trial functions, the first type is the positive quadratic functions, which can be used to obtain lump solutions and rogue wave solutions. The second type is the superposition of positive quadratic functions and positive arbitrary functions, resulting in an interaction solution consisting of both rational solution and arbitrary function solutions. We will provide examples to illustrate the interaction solutions formed by the superposition of positive quadratic and exponential functions, the superposition of positive quadratic, exponential and trigonometric functions, and the superposition of positive quadratic, exponential, trigonometric and hyperbolic functions. In short, we constructed different trial functions, so various new superposition solutions and wave motion were obtained.

This paper presents the design and demonstration of 1 × N (N = 2, 4) dual-mode optical switches on a silicon-on-insulator platform, optimized for mode division multiplexing (MDM). The switches utilize a multimode interference-based Mach-Zehnder interferometer combined with thermo-optic phase shifters for efficient mode control. For the elementary 1 × 2 switch, an insertion loss of less than 0.06 dB for the TE₀ mode and 0.10 dB for the TE₁ mode is achieved within the C-band, with crosstalk levels below − 30.5 dB for both modes. Scalability is demonstrated with a 1 × 4 switch, where the insertion loss is reduced to 0.61 dB for TE₀ and 0.48 dB for TE₁, and crosstalk is kept below − 37.9 dB for TE₀ and − 35.5 dB for TE₁ across all switching configurations. The switches are designed using the Lumerical Heat Solver module and the Eigenmode expansion method. With compact footprints of 6.5 × 750 μm² for the 1 × 2 switch and 15 × 1400 μm² for the 1 × 4 switch, these switches offer significant potential for intra-chip MDM systems and photonic integrated circuits.