Optical and Quantum Electronics最新文献

We analyze the effects of a randomly inhomogeneous spatial variation of the electrostatic potential across the flat surface of a doped graphene sheet on the spectral shape of its plasmon resonance in the terahertz to the mid-infrared frequency range. This is achieved by solving the plasmonic eigenvalue problem based on a position-dependent Drude conductivity of graphene, coupled with a stochastic description of the underlying random potential landscape, which is parameterized by a variance and a correlation length. We computed a frequency– and wavenumber–dependent spectral density, which exhibits strong nonlocal effects due to both the variance and the correlation length. Those parameters were found to play comparable roles in the plasmon line broadening and that they can give rise to the blue– or red–shifting of the plasmon peak. We also found that a substantial asymmetry develops in the plasmon spectra with increasing the disorder parameters and increasing frequency, causing a sizeable uncertainty in the positions of the peak and the mean values of those spectra in relation to the plasmon dispersion of clean graphene. The inclusion of the correlation length and the analysis of the spectral asymmetry are novel aspects of our work that were largely ignored in previous studies of the disorder effects in graphene plasmonics.

A concept for the generation of short, relativistically strong femtosecond pulse is proposed. Self-compression, group velocity dispersion (GVD) and self-phase modulation (SPM), are given particular attention in the study. The interaction of Cosh-Gaussian laser with plasma, causes a change in the phase of the laser pulse and alters the plasma’s refractive index, leading to laser pulse spectral broadening. It is worth noticing that, the laser in plasma shows opposite GVD compared to other media like solid. This exclusive behavior permits laser pulse to experience dispersion compensation while broadening the spectrum, eventually leading to self-compression. The numerical model, performed using the paraxial approach demonstrates how these phenomena contribute to the self-compression of a 200 fs laser into a 20.4 fs laser pulse. Unlike the optical components in Chirped-Pulse Amplification (CPA), plasma is resistant to damage from intense laser exposure. These results have the potential to be a scheme for generating high intensity short laser pulses.

This paper examines the impact of excess carrier injection on the linear refractive index and linear absorption of n-type and p-type silicon within the wavelength range of 1 to 8 μm. By implementing empirical models and utilizing existing data, we have determined the contributions of excess carriers to linear absorption and linear refractive index, and we have analyzed how these parameters change at different carrier concentrations across the wavelength range. The results calculated using the proposed functions align well with available experimental data. Our findings illustrate that both the refractive index and linear absorption significantly change, particularly at longer wavelengths, due to increasing carrier concentrations. Notably, the absorption coefficient for n-type silicon increases more significantly compared to that of p-type silicon as the carrier concentration rises. Conversely, the changes in the refractive index behave oppositely for n-type and p-type silicon. Using the developed method, one can optimize the design and performance of electro-optical devices, particularly in the near- and mid-infrared regions.

Despite advances in terahertz metamaterial sensors, most designs remain limited by narrow functionality, complex fabrication and restricted sensitivity for biomedical diagnostics. This study presents a cost-effective terahertz metasurface biosensor engineered for high-sensitivity multi-disease detection. The device integrates four concentric octagonal resonators fabricated in aluminum on a low-loss polyimide spacer backed by a metallic ground plane, achieving three distinct resonance peaks. Optimization yielded sensitivity exceeding 1.18 THz/RIU and quality factors above 13, with complete polarization insensitivity and angular stability up to 60°. The sensor demonstrates reliable detection of hemoglobin level variations associated with anemia and other blood disorders, a diverse array of pesticide residues and organic solvents and bacterial contaminants such as Escherichia coli and Pseudomonas aeruginosa. Its sensitivity and stability further support potential applications in monitoring metabolic conditions such as diabetes, detecting infectious agents and screening environmental pollutants. Consistent resonance responses across all tested analytes shows the design’s effectiveness for rapid, noninvasive analysis. This versatile approach holds promise for high-end sensing in clinical diagnostics, food safety and environmental surveillance.

We study theoretically the analytical expression of a pulsed chirped modified anomalous vortex beam (MAVB) across biological tissue using the integral of Huygens-Fresnel and the Fourier Transform method. Spectral modifications for pulsed chirped MAVB are examined across various biological tissues, including human upper dermis, mouse intestinal epithelium, and mouse deep dermis. Graphical representations are employed to analyze the beam parameters, biological tissue effect properties, and transverse positions on the analyzed beam. Results reveal that the structure constant of refractive index, chirp parameter, pulse duration, and variations in beam parameters can impact the intensity of the spectral beam. The on-axis spectral intensity shows a blue shift, whereas the off-axis spectral intensity demonstrates a red shift as the radial coordinates increase. It is expected that the results of this study will greatly enhance progress in disease and treatment, particularly in cancer research. By analyzing variations in intensity distribution, scientists can improve their ability to identify and diagnose diseases more effectively.

Organic semiconductor blends offer a promising platform for low-cost and environmental friendly optoelectronic devices, yet their performance is often limited by incomplete spectral absorption and suboptimal charge-transfer characteristics. In this work, we investigate the optical and structural properties of two binary blends (VOPcPhO: PC₇₁BM and PCDTBT: PC₇₁BM) and a ternary blend (VOPcPhO: PCDTBT: PC₇₁BM) to identify the advantages of combining complementary donor materials in a bulk-heterojunction system. The ternary film exhibits markedly enhanced photoactive behavior, achieving a high absorption coefficient of ~ 1.8×10⁵ cm^− 1 at 3.56 eV, a refractive index of ~ 2.4, and an extinction coefficient of ~ 3.54 × 10⁴ cm^− 1. Its optical conductivity increases to ~ 6.43 × 10¹⁵ S·cm^− 1, surpassing both binary counterparts. Improved film morphology and favorable energy-level alignment further promote stronger light-matter interaction and more efficient charge-transfer pathways. These combined enhancements demonstrate that the VOPcPhO: PCDTBT: PC₇₁BM ternary blend outperforms the binary systems in both optical response and structural quality, highlighting its strong potential as an effective active layer for next-generation high-performance optoelectronic devices.

The ability of structured light to reconstruct after partial obstruction, known as the self-healing phenomenon, has attracted considerable attention for applications in imaging, optical communication, and quantum technologies. While Bessel and Airy beams have been extensively studied, the self-healing behavior of Hermite–Gauss (HG) beams remains less well quantified. In this work, we systematically investigate the self-healing properties of six HG modes (HG₀₁, HG₁₀, HG₁₁, HG₁₂, HG₂₁, HG₂₂) under three classes of obstructions: circular disks, vertical strips, and rectangular fringes. Both intensity- and amplitude-based similarity measures are employed within the normalized self-healing degree (SHD) framework, providing a rigorous and comparable metric of recovery efficiency. Numerical simulations reveal that higher-order modes, particularly HG₂₂, demonstrate superior resilience, achieving SHD values above 1.1 even for moderate obstructions, whereas lower-order modes exhibit incomplete recovery. Geometry–mode alignment effects are also observed, with HG₁₁ showing enhanced robustness under strip obstructions. Importantly, amplitude-based SHD is consistently lower than intensity-based SHD, confirming that apparent intensity recovery can overestimate robustness when phase fidelity is critical. These findings establish a comprehensive quantitative picture of HG self-healing and offer practical insights for designing resilient, structured beams in realistic optical environments.

This study proposes a wideband graphene-based metasurface absorber on a quartz substrate, offering enhanced absorption, intrinsic tunability, and suitability for advanced sensing and biomedical diagnostics. Unlike conventional absorbers requiring external components, its resonance frequency is dynamically tuned by varying graphene’s relaxation time (0.1–0.3 ps), enabling efficient frequency modulation with simplified structure. The metasurface demonstrates high sensitivity to refractive index variations of hemoglobin and urine, directly linked to clinically relevant parameters such as glucose and uric acid. It achieves maximum sensitivity of 2.0 THz/RIU (FOM = 11.1/RIU) for hemoglobin and 6THz/RIU (FOM = 24/RIU) for urine. Additionally, it enhances SNR and suppresses EMI, improving MRI imaging. These features establish it as a promising platform for next-generation terahertz sensing and EMI-shielding applications.

Undoped and Co-doped ZnO films were deposited on glass substrates by dip-coating. The sol-gel technique was employed to prepare a series of precursor solutions by dissolving zinc acetate dihydrate (ZnAc) and stochiometric amounts of cobalt acetate dihydrate (CoAc) in 2-methoxyethanol to achieve target Co concentrations of 1, 3, 5, and 7 wt%, with the addition of mono-ethanolamine (MEA) as a stabilizer. All films were subsequently annealed for 2 h 30 min at 500 °C. To investigate the effect of Co doping, and understand the morphological, structural, and optical characteristics of the films, several techniques were employed. The X-ray diffraction (XRD) patterns of all films showed hexagonal crystals of the ZnO wurtzite phase with nanometric crystallite sizes (less than 20 nm). The AFM images revealed irregularly shaped grains with a non-uniform surface distribution. All samples exhibited high transmittance in the visible region and a strong absorption edge in the UV region. Photoluminescence (PL) spectroscopy revealed a non-monotonic evolution of the UV emission and a general quenching of the visible band with Co concentration. Photocatalysis showed a progressive improvement as the Co doping increases. In contrast, the antibacterial activity revealed a divergence at 7% doping, where efficacy against E. coli decreased while the inhibition of S. aureus continued to increase.