Optical and Quantum Electronics最新文献

Chalcogenide glass samples shaped as thin discs of the Ga₃Ge₂₅As₁₅Se₅₇ composition, undoped and doped with samarium ions (Sm³⁺) at concentrations of 0, 750 and 1700 ppmw, were illuminated with S- or P-polarized light in the range of wavelengths of 0.5–1.8 μm near the fundamental absorption band edge. The transmittance and reflectance measurements were validated by comparison with a theoretical model example that takes into account the refractive index dispersion, polarization-dependent Fresnel reflections, and an absorption band at a specific frequency. Based on the measurement results, spectral dependences of the attenuation coefficients and refractive indices of the doped and undoped glasses were calculated. The scattering coefficients corresponding to the “gray” losses, estimated by analyzing the microstructure studied in the bulk of glass samples using IR 3D microscopy, were subtracted from the attenuation coefficients to obtain the absorption coefficients at the edge of the fundamental absorption band and to estimate the bandgap energy and the Urbach tail parameter of the glasses. It was found that the scattering coefficients decrease with increasing Sm³⁺concentration. The absorption coefficients depend on the ion concentration at the low-frequency edge of the Urbach tail and at the weak absorption tail between the absorption bands of Sm³⁺. A slight separation of the spectral dependences of the refractive indices and absorption coefficients measured at different light polarizations was obtained for both undoped and doped glasses. It was found that the glass doping with such Sm³⁺concentrations does not affect zone-zone transitions in the glass, but changes the density of localized states in the bandgap.

Transparent conducting indium zinc oxide (IZO) films often suffer from unstable carrier concentration, defect-induced scattering, and limited mobility, which restrict their suitability for high-performance optoelectronic devices. Rare-earth doping is a promising strategy to improve lattice stability and electronic transport; however, the combined effect of Cerium (Ce) and Erbium (Er) co-doping in IZO thin films remains insufficiently explored. This work aims to investigate how Ce–Er co-doping influences the structural, optical, electrical, and surface electronic properties of sputtered IZO films and to identify the optimal dopant configuration for transparent electrode applications. Ce–Er co-doped IZO thin films were deposited by RF magnetron sputtering and systematically characterized. XRD confirmed a highly crystalline cubic bixbyite In₂O₃ phase with preferred (222) orientation. A progressive shift of diffraction peaks toward higher 2θ values and lattice contraction from 10.11 to 9.94 Å indicated substitutional incorporation of Ce³⁺ and Er³⁺ ions. AFM revealed dense, uniform surfaces with RMS roughness of 3.4–4.8 nm and grain sizes reaching 65.68 nm for the Ce30W–Er30W composition. The films exhibited high optical transparency (> 96%) and a slight bandgap widening from 3.56 to 3.68 eV due to the Burstein–Moss effect. Hall measurements confirmed n-type behavior with carrier concentrations up to 2.15 × 10²⁰ cm⁻³, mobility of 27.15 cm² V⁻¹ s⁻¹, and a low resistivity of 1.05 × 10⁻³ Ω·cm. Scanning Kelvin probe analysis further showed an increase in work function from 4.04 eV (undoped) to 4.77 eV for the most conductive composition. These results demonstrate that moderate Ce–Er co-doping effectively tailors lattice strain, carrier transport, and surface energetics, enabling highly transparent, low-resistivity IZO films suitable for next-generation optoelectronic and photovoltaic devices.

We study the four-wave mixing of a semiconductor quantum dot featuring a cascaded exciton–biexciton system in the vicinity of a gold spheroidal nanoparticle, assuming the interaction of the system with a strong pump field and a weak probe field both polarized along the interparticle axis. We express the density matrix equations in a rotating frame under the dipole approximation and apply a perturbative expansion to evaluate the element related to the four-wave mixing optical process. Next, we investigate the dependence of the spectral characteristics on the geometrical parameters of the metal nanoparticle (MNP), considering various interparticle distances, under one-photon, two-photon, or combined resonance conditions. To interpret the emergence of the observed spectral features, we further develop a dressed-state framework and analyze the results based on the theory of plasmonic metaresonances, providing a transparent physical understanding of the underlying exciton–plasmon resonance mechanisms.

In this work, we present a tunable plasma-induced transparency (PIT) metamaterial architecture, ingeniously engineered from a graphene-based split-ring resonator metasurface. The core design integrates a leftward compact split-ring resonator (LSR) with its complementary rightward expanded counterpart (RSR), both meticulously tailored to stimulate planar bright modes. Simulations conducted using CST Studio Suite 2023 corroborate our theoretical framework, as Coupled Mode Theory (CMT) adeptly models the observed PIT spectral features. A thorough investigation into the geometrical dependencies revealed that parameters such as the inner and outer radii of the open rings, alongside the inter-resonator coupling distance, significantly influence the transmission spectrum. Notably, the tunability of the PIT window is achieved through modulation of the graphene’s Fermi level, underscoring the structure’s adaptive capabilities. The metamaterial exhibits a measurable slow-light effect, with a peak group delay of 0.642 ps. While this delay is moderate compared with multilayer or multi-resonator designs, it nonetheless demonstrates that the proposed structure can achieve useful dispersion control within a compact and simplified configuration. From a sensing perspective, our devices demonstrate excellent performance, characterized by a high refractive index sensitivity (7.88THz/RIU)and a reasonable figure of merit (FOM) (37.9RI{U^{ - 1}}), thereby affirming their suitability for advanced optical modulators, precision slow-light systems, and cutting-edge terahertz sensor technologies. These findings collectively underscore the promise of this graphene metamaterial platform in photonic device landscapes.

This study investigates the channel impairments associated with underwater wireless optical communication (UWOC). It focuses on issues such as attenuation effects, pointing errors (PEs), angle-of-arrival (AOA) fluctuations, and turbulence. These impairments are modeled using the Beer–Lambert Law, Hoyt distribution, Rayleigh distribution, and Fisher-Snedecor F-distribution, respectively, to enhance the performance of UWOC. The F-distribution is employed to model the probability distribution of a spherical wave as it propagates through asymmetric oceanic turbulence, offering a flexible framework for various turbulence intensities. The study derives key performance metrics, such as outage probability (OP), throughput, and ergodic capacity (EC), using Meijer-G and Fox-H functions. At high SNR (75–90 dB), the OP is observed to be (P_{out} approx 1.8times 10^{-4}) for chlorophyll concentrations of 0.006, 0.1, and 0.5 mg/m(^{3}). A significant improvement in throughput is noted, with (omega _b/ r_a = 3) achieving a throughput of 0.99607 at an SNR of 45 dB, compared to 0.32644 for (omega _b/ r_a = 13). The receiver field-of-view angle (FoV) is found to influence AOA fluctuations, with the EC remaining stable (EC(approx )20) despite beam misalignment ratios ((q_H)) varying from 0.1 to 1. Additionally, the study demonstrates that Heterodyne Detection (HD) outperforms Direct Detection (DD), and that narrowing beamwidths significantly improve received signal power and EC, offering a practical approach to optimizing the performance in real-world conditions.

Newly shaped solitons and rogue waves on several periodic background in the reduced spin Hirota–Maxwell–Bloch (rsHMB) system are presented. First, various seed solutions of the rsHMB system are established, including constant solutions and four types of Jacobian elliptic function solutions. Then, by means of the nonlinearization of Lax pairs and the Darboux transformation (DT) method, the general expressions of (q(x, t)) and (eta (x, t)) are derived by corresponding several seed solutions including constant solutions, dn, cn, nd and sd solutions, respectively. N-shaped solitons, M-shaped solitons, W-shaped solitons, multi-peaked solitons as well as rogue waves on dn, cn, nd and sd periodicity are obtained, and the characteristics and dynamic behaviors of these solutions are explained.

This work presents a compact, cost-effective approach to a tunable single-longitudinal-mode (SLM) dual-wavelength fibre laser (DWFL) with ultra-narrow linewidth and a high optical signal-to-noise ratio (OSNR). The proposed system provides a novel double-peanut-shaped (DPS) in-line comb filter based on a polarisation-maintaining fibre (PMF) combined with an unpumped erbium-doped fibre (EDF) serving as a saturable absorber (SA) for SLM dual-wavelength generation. The DPS filter generates a comb-like spectrum with a free spectral range (FSR) of approximately 5 nm. This enables narrow linewidth dual-wavelength lasing at 1557.69 nm (λ₁) and 1562.71 nm (λ₂) with an OSNR of 70 dB, without the need for complex compound cavity filters. Wavelength tunability over a 20 nm range is achieved by adjusting the polarisation controller (PC). Experimental results demonstrate ultra-narrow linewidths of 375 Hz and 455 Hz for the two lasing wavelengths, as measured by a delayed self-heterodyne interferometry system (DSHI). The proposed design offers a significant performance in terms of OSNR, linewidth, and tuning range, representing its potential for advanced applications in microwave photonics, optical sensing, and 6G wireless communication systems.

This study presents a comprehensive theoretical investigation into the linear and nonlinear optical properties of Boron Arsenide Nanotubes (BAsNTs) under an external axial magnetic field, establishing them as a superior alternative to Carbon Nanotubes (CNTs) for advanced optoelectronic applications. Employing a tight-binding framework in combination with the density matrix formalism, we demonstrate that an axial magnetic field induces a significant and tunable Aharonov-Bohm splitting in all optical spectra. Our findings reveal that BAsNTs exhibit an intrinsically stronger third-order nonlinear optical response, including the DC Kerr effect, Two-Photon Absorption (TPA) and Third-Harmonic Generation (THG), compared to CNTs of similar chirality. The applied magnetic field enables precise tuning of resonance positions and enhances the intensity of these nonlinear phenomena, with Two-Photon Absorption and Third-Harmonic Generation spectral intensities amplified by up to five-fold. The remarkable finding is the ability to magnetically control the interaction and coupling of multi-photon resonances of different orders. These findings highlight the potential of BAsNTs as a robust, chirality-independent tool for developing next-generation tunable nanophotonic devices, such as magneto-optical modulators, frequency converters, and all-optical switches.

PVA (Polyvinyl alcohol) and PVP (polyvinyl pyrolidone) blend films filled with different concentrations of Cr (0.16 to 3.125 wt%) were prepared by the solution casting technique. X-ray diffraction patterns of Cr-doped PVA-PVP films exhibit a diffraction peak at ~ 19.83° with a (1 0 1) orientation, indicating a semicrystalline nature. The increase in Cr doping concentration in PVA-PVP films exhibits an amorphous nature. The pore-free surface morphology of the films shows an agglomeration due to the Vander Waals force between the Cr³⁺ ions and the PVA-PVP host matrix. A shift in the absorption edge towards longer wavelengths results in a reduction of the optical band gap from 3.68 to 3.44 eV. The reduction of the optical band gap with increased Cr content in PVA-PVP film was attributed to the introduction of defect states and localized energy levels in the band structure, increased disorder and band tailing, and enhanced charge transfer interactions. Wemple DiDomenico and Sellmeier’s single oscillator models were used to determine the optical dispersion parameters. The linear, nonlinear optical dispersion parameters, and optoelectrical parameters were enhanced due to the Cr dopant in PVA–PVP films.