Optical and Quantum Electronics最新文献

We compute the optical absorption, density of states and optical coefficients of graphene armchair nanoribbon under spin-orbit coupling effects. Kane–Mele model Hamiltonian has been applied for obtaining electronic band structure of graphene armchair nanoribbon in the presence of magnetic field and gap parameter. The effects of magnetic field and spin-orbit coupling strength on the frequency behavior of optical absorption of graphene armchair nanoribbon have been investigated. Also the frequency behavior of optical absorption of gapped graphene armchair nanoribbon has been studied due to magnetic field, spin-orbit coupling and gap parameter. Linear response theory and Green’s function approach have been exploited to obtain the frequency behavior of optical behavior of the structure. Moreover, the transmissivity and reflectivity of electromagnetic wave between two media separated by a graphene armchair nanoribbon are given. Our numerical results indicate that the frequency dependence of optical absorption includes a peak due to applying magnetic field. Also the frequency dependence of transmissivity and reflectivity of electromagnetic wave between two media separated by graphene armchair nanoribbon for normal incidence has been investigated due to effects of magnetic fields and spin-orbit coupling.

This study examines the role of electric dipolar interactions in controlling quantum entanglement and coherence in doped graphene systems. It demonstrates that quantum coherence, which is more resilient than concurrence, remains stable at higher temperatures, making it a crucial resource for quantum technologies. The dipolar interaction plays a key role in maintaining both coherence and concurrence, particularly by enhancing coherence at elevated temperatures. These findings highlight the importance of engineering interactions that preserve coherence, even in fluctuating environments. Overall, quantum coherence is identified as essential for the development of robust doped graphene-based quantum technologies, with promising applications in quantum information processing.

This study thoroughly examines the effectiveness of iodine-based dopants in dye-sensitized solar that utilize titania aerogel by linking the material characteristics altered through the interaction of iodine with the surface and lattice structures. The surface-adsorbed iodine functionalized titania aerogel, designated as AI, while the lattice incorporated iodine and potassium ions in the titania aerogel and labeled it LI. The LI-based photoanode demonstrated an improved dye loading capacity of 0.43 µmol/mg and a significantly higher device efficiency of 4.34%, in contrast to the AI-based device, which achieved an efficiency of 1.66%. The spectroscopic analysis showed notable broadening and redshift in the absorption spectra for LI, suggesting robust electronic coupling and dye aggregation, which enhanced photon absorption and electron injection efficiency. Electrochemical impedance spectroscopy revealed a reduced charge transfer resistance (R_Ct = 29.5 Ω) and an increased electron lifetime (τ_n = 27.4 ms) for the LI-based DSSC, leading to enhanced interfacial charge transport and minimized recombination. The findings underscore the importance of the photoanode’s surface characteristics and the dyes’ aggregation for improving the performance of dye-sensitized solar cells. This study identifies LI-based photoanodes as strong contenders in enhancing the efficiency of DSSCs, offering valuable insights into optimizing charge dynamics and photochemical stability.

Organic/inorganic halide perovskites (OIHP), including the composition of methylammonium lead iodide bromide (MAPbI₂Br), have gained increasing popularity in solar applications because to their exceptional optoelectronic characteristics. Despite the persistence of recombination losses and stability issues, MAPbI₂Br remains a viable choice due to its bandgap of around 1.8 eV. The objective of this study is to examine the process of introducing 6% chromium (Cr) into MAPbI₂Br in order to address the aforementioned challenges. X-ray diffraction (XRD), current-voltage (J-V), and ultraviolet-visible spectroscopy (UV-vis) studies have demonstrated improved structural, optical, and photovoltaic characteristics of perovskite films doped with 6% Cr. The observed decrease in bandgap (from 1.99 to 1.94 eV) as the crystal size grows (from 21.45 to 32.09 nm) may be attributed to quantum size effects. The band structures of electronic materials undergo changes as the crystal size increases and the confinement of electrons decreases, leading to alterations in the bandgap energy. The Cr–MAPbI₂Br device achieves an efficiency of 8.36%, surpassing the 7.40% efficiency of pure MAPbI₂Br. This is a significant advancement towards enhancing the safety and effectiveness of perovskite solar cells.

Mn/Co/SnSe nanoparticles were synthesized using the co-precipitation method with the ratios Mn_xCo_ySn_{(1−x)(1–y)}Se (where x = 0.1–0.5 and y = 0.1–0.5) coded MCSS-1, MCSS-2, MCSS-3, MCSS-4 and MCSS-5 nanoparticles. Mn_xCo_ySn_{(1−x)(1−y)}Se nanoparticles were characterized with X-ray diffraction (XRD), UV-absorbance spectroscopy, and scanning electron microscopy (SEM). The XRD analysis revealed that the Mn_xCo_ySn_{(1−x)(1−y)}Se nanoparticles possess an orthorhombic structure, with average crystallite sizes below 100 nm. The SEM images showed that the surface morphology of the Mn_xCo_ySn_{(1−x)(1−y)}Se nanoparticles was not perfectly spherical, displaying small spherical shapes and rod-like structures. The optical properties were examined using UV–Vis spectroscopy, indicating that the highest absorbance occurred between 200 and 400 nm. The cyclic voltammograms (CV) graph shows the pseudocapacitance nature of the Mn_xCo_ySn_{(1−x)(1−y)}Se nanoparticles. The MCSS-1 electrode has a coulombic efficiency and capacitive retention of 93% and 94.98% whereas the MCSS-4 electrode has 95% and 96.68%. The increase in the coulombic efficiency and capacitive retention from MCSS-1 to MCSS-4 electrodes show an increasing tendency with the incorporation of dual-doped Mn/Co dopants.

This paper presents an all-optical 4 × 2 encoder based on metal–insulator–metal (MIM) waveguides, designed for operation across a wide wavelength range of 1–2 μm. The MIM waveguides consist of SiO₂ dielectric strips sandwiched between layers of silver metal. The encoder incorporates a straight waveguide to detect the state of the In₀ input. Additionally, it includes one splitter and two combiners with outputs Out₀ and Out₁ for detecting the states of the In₁, In₂, and In₃ inputs. A key innovation in this work is the distance created between the splitter and combiners, which allows for tuning and improving the encoder output characteristics. The proposed encoder was simulated using the finite-difference time-domain method. It demonstrates a minimum extinction ratio of 11.65 dB and a crosstalk level of − 15.65 dB at a wavelength of 1550 nm. The total footprint of the encoder is less than 8 μm². Our research indicates that a 4 × 2 encoder utilizing MIM waveguides has not been previously reported. Given its straightforward fabrication process, high extinction ratio, and low crosstalk, the suggested encoder is a promising candidate for a wide range of plasmonic communication and signal-processing applications.

This study presents the design and optimization of multi-functional all-optical NOT and XOR logic gates based on interference effects within two-dimensional photonic crystal structures. Our approach aims to address the growing demand for high-performance components in next-generation photonic integrated circuits (PICs). We enhanced the structure’s applicability and performance by carefully optimizing the output waveguide configuration. Our design achieved impressive performance metrics, including a response time of approximately 0.15 ps, a contrast ratio of 32.88 dB, and a bit rate of roughly 6.67 Tbit/s. Notably, the compact size of 83.55 μm² makes our design particularly suitable for PICs. To demonstrate the versatility of our approach, we developed an optimized 4 × 2 encoder based on the same design principles. This more complex structure with a compact size of 133.67 μm² exhibited a contrast ratio of approximately 26.54 dB, further validating the flexibility and practicality of our designs for integration into optical circuits. Our methodology employed the plane wave expansion method for determining and analyzing the photonic bandgap range. In contrast, the finite-difference time-domain method was utilized to simulate and evaluate the proposed structures’ performance. These results collectively demonstrate the significant potential of our designs for future PIC applications, offering a promising pathway toward high-performance, integrated optical computing systems.

The trajectory of magnetic flows that generate a magnetic field is called a magnetic curve. In this paper, a new class of electromagnetic curves is defined through a new frame defined along polynomial curves, called the Flc frame. Moreover, given that an optical fiber is a one-dimensional object placed on a three-dimensional Riemannian manifold, the evolution of a linearly polarized light wave is related to the geometric phase. Therefore, a new geometric phase model is obtained using the Flc frame.