Optical and Quantum Electronics最新文献

This paper examines the influence of atmospheric turbulence on the characteristics of a new laser beam called a modified anomalous vortex beam (MAVB). An analytical expression for the MAVB’s propagation through atmospheric turbulence is derived using the extended Huygens-Fresnel principle and the Rytov method. Numerical simulations were performed to examine the impact of atmospheric turbulence and incident beam parameters on the average intensity of the MAVB. The results reveal that the received intensity is influenced by the structure constant of the turbulent atmosphere, propagation distance, and incident beam parameters, including the beam waist, topological charge, beam order, and modification parameter. It is demonstrated that the MAVB gradually loses its initial shape during propagation, transforming into a Gaussian-like beam at greater distances. The central peak rises more rapidly when the turbulence constant strength, modification parameter, or beam order is larger, while the Gaussian width or topological charge is smaller. The results can benefit atmospheric optics applications like free-space optical communications and remote sensing.

This study introduces an artificial intelligence (AI)-based approach for high-precision alignment of Panda polarization-maintaining optical fibers. Using the YOLOv8 model for object detection, our method effectively aligns the slow axis of the Panda fiber with the edge of a pre-designed groove, which is essential for preserving polarization properties in optical communication and sensing applications. A 1000× microscope camera captures images of the fiber and groove, allowing the AI model to accurately detect the angle between the fiber’s slow axis and the groove edge. This angle information is then used to control a motor that rotates the fiber until alignment is achieved. Extensive experiments reveal that our system achieves an angular alignment error of < 2°, limited mainly by image quality and groove irregularities. This automated alignment system, driven by a deep learning model, offers significant improvements over traditional methods, optimizing alignment accuracy and operational efficiency and presenting new possibilities for the integration of AI in photonic device fabrication.

The computation of the propagation of an electromagnetic wave in the time domain is examined using local Faber polynomial based time dependent propagators. Conventionally, the whole computational domain is evaluated by one global operator. Contrary, when utilizing a nonuniform discretization in the system local operators can be used individually for each subarea. This allows the complexity to be reduced by decreasing the polynomial order of the evaluation of the Faber algorithm, while at the same time decreasing the overall runtime. Compared to common Local Time Step methods, the time step size of each individual area with this approach is already synchronized with a predefined global time step size. In general, the investigated approach is especially interesting for applications that demand a high spatial resolution, such as in the field of nanophotonics and THz-technology. However, the influence of the necessary process steps on the runtime must be examined in particular when computing with the local operators approach. To this end, the theoretical complexity is derived and compared with practical results to analyze the efficiency.

In this paper, the curved Optical waveguide is analyzed for the first time having a complicated chirp type of the refractive index profile in the fiber core. The finite difference method in conjunction with the conformal transformation has been devised to extract the allowed Eigen values and Eigen vectors of the waveguide. This paper studies the effect of bending radius on b-V graph characteristics, power confinement factor, and mode field profile for better suitability for next-generation optical network systems.

This article presents the design of five new π-conjugated molecules whose structure contains a D-Pi-D succession, where the donor D unit consists of a carbazole, and the Pi unit varies according to the different donors. Parameters examined included HOMO (Highest Occupied Molecular Orbital) and LUMO (Lowest Unoccupied Molecular Orbital) energy levels, band gap energy (Egap), frontier molecular orbitals, electron affinity and ionization potential. The results show that the Egap values of the molecules studied range from 3.34 to 4.11 eV, suggesting strong conjugation of these structures. The Time-Dependent Density Functional Theory using the B3LYP hybrid functional and the 6-311G(d,p) basis set method was used to analyze the absorption and emission properties of the compounds, highlighting various features such as their maximum wavelength (λmax), vertical excitation energy (E) and oscillation strengths (O.S), maximum emission wavelengths (λem) and fluorescence energies (EFLu). These materials exhibit broad absorption bands above 360 nm and intense emissions above 421 nm, falling into the UV–visible region. Analysis of the I–V characteristic obtained by SILVACO TCAD software indicates that a minimum voltage is required for the organic light-emitting diode (OLED) to emit light, with threshold voltages of VD = 2 V and VD = 2.2 V. The results show that Oi compounds possess promising properties, makes them potentially interesting materials for use in OLED devices. This theoretical study therefore provides a valuable framework to guide the experimental synthesis of these compounds.

This paper presents the design and optimization of a graphene-based broadband absorber aimed at enhancing light absorption across the visible to near-infrared spectrum. The proposed structure features a metal film array with annular and L-shaped grooves that intensify electromagnetic fields and amplify local surface plasmon resonance. This leads to improved interaction between light and the graphene layer. To achieve optimal performance, the design process involved the use of the particle swarm optimization algorithm. This powerful tool fine-tunes the geometric parameters, including the thickness, length, and width of the grooves, with precision and rigor. The optimized structure, comprising chromium as the metal film and Al₂O₃ and TiO₂ as groove fillers, achieved an average absorption rate of 85.79%, a significant improvement over the initial average absorption of 74.33%. This design not only demonstrates substantial potential for applications in photonics, sensing, and energy harvesting but also offers an effective solution for broadband absorbers with high efficiency. Moreover, the innovative integration of graphene with annular and L-shaped grooves to concentrate and amplify electromagnetic fields highlights a key advancement in absorber design.

The commercial suitability of lead halide perovskites is deprived by stability and toxicity concerns despite their extraordinary physiochemical features and improved power conversion efficiency. There is an increasing preference towards reliable and ecologically sustainable alternatives with comparable optical and electronic characteristics. For this purpose, our study is concerned with identifying physical characteristics like structural, electronic, mechanical, and optical characteristics of FrBF₃ (B = Ge, Sn) under varying pressures up to 40 GPa. Both FrGeF₃ and FrSnF₃ have cubic crystal structures and their atomic bond length reduces with increasing pressure as lattice constant, and volume reduces with the application of hydrostatic pressure. They are structurally and mechanically stable in all the variations of pressure. Initially, both compounds have direct bandgap where FrGeF₃ has 2.14 eV bandgap and FrSnF₃ has 1.83 eV bandgap. The impact of pressure on band structure is notable as both compounds go through a linear transition from semiconductor to metal by concentrating electronic states at the Fermi level. The absorption, extinction coefficient, and optical conductivity also shift towards lower photon energy (redshift), which makes them viable options for solar cell development and optoelectronic devices under pressure as they can absorb photon energy of infrared and visible range. Besides, their mechanical features including elastic moduli, ductility, and anisotropy improve linearly with pressure. The findings of our study suggest that the perovskite FrBF₃ (B = Ge, Sn) exhibits an excellent improvement of mechanical, electronic, and optical characteristics when introduced to hydrostatic pressure, making them suitable for many real-life applications such as photodetector, sensor, energy storage devices, solar panels and other optoelectronic devices.

This paper investigates the entanglement and quantum steering of an hybrid quantum system consisting of a pair of initially entangled atoms interacting inside a cavity in the presence of a magnon field and an external classical field. By solving the system using the master equation, the density operator of the total system is obtained. Using negativity and the Einstein-Podolsky-Rosen steering criterion, the time evolution of entanglement and steering between the two atoms as well as between the cavity field and the magnon are calculated. Our results show that the entanglement and steering between the atoms can be controlled by changing the coupling of the external classical field and the cavity-magnon system, where increasing them leads to the improvement of both steering and entanglement behaviors. On the contrary, increasing the cavity-magnon coupling weakens both the steering and entanglement between the fields, while adding the external classical field leads to increasing the field system’s randomness. We also observe that adding the surrounding environment destroys the entanglement and steering between both the atoms and the fields. Furthermore, bidirectional steering between the atoms contrasts with one-way steering of the fields, contingent upon system parameters.

We investigate the propagation of an ultrashort optical pulse using Fokas-Lenells equation (FLE) under varying dispersion, nonlinear effects and perturbation. Such a system can be said to be under soliton management (SM) scheme. At first, under a gauge transformation, followed by shifting of variables, we transform FLE under SM into a simplified form, which is similar to an equation given by Davydova and Lashkin, we refer to this form as DLFLE. Then, we propose a bilinearization for DLFLE in a non-vanishing background by introducing an auxiliary function which transforms DLFLE into three bilinear equations. We solve these equations and obtain dark and anti-dark one-soliton solution (1SS) of DLFLE. From here, by reverse transformation of the solution, we obtain the 1SS of FLE and explore the soliton behavior under different SM schemes. Thereafter, we obtain dark and anti-dark two-soliton solution (2SS) of DLFLE and determine the shift in phase of the individual solitons on interaction through asymptotic analysis. We then, obtain the 2SS of FLE and represent the soliton graph for different SM schemes. Thereafter, we present the procedure to determine N-soliton solution (NSS) of DLFLE and FLE. The graphical representation of the soliton shows great potential of SM scheme to manipulate the pulse. Later, we introduce a Lax pair for DLFLE and through a gauge transformation we convert the spectral problem of our system into that of an equivalent spin system which is termed as Landau–Lifshitz (LL) system. LL equation (LLE) holds the potential to provide information about various nonlinear structures and properties of the system.

In this paper, we propose a novel and general approach for designing flat-top (de)multiplexers, particularly (de)interleavers, utilizing a Photonic Crystal Mach-Zehnder Interferometer (PC-MZI) based on multimode interference (MMI). We demonstrate the design and performance of 4-, 6-, 8-, and 16-channel PC-MZI (de)interleavers with minimal loss, low crosstalk, and a flat-top transmission spectrum achieved through a hexagonal photonic crystal structure. Simulation results at a central wavelength of 1.55 µm reveal 1 dB and 3 dB bandwidths of 3.3 nm and 7 nm for the 4-channel, 8.1 nm and 14 nm for the 6-channel, and 2.5 nm and 4.3 nm for the 16-channel (de)interleavers, respectively. Furthermore, the 16-channel device exhibits channel spacing of 11 nm between adjacent channels and 22 nm for non-adjacent channels separated by one intervening channel. Finally, we achieve power losses ranging from 0.05 dB to 3 dB and channel isolation between − 10 dB and − 22 dB.