arXiv subjects

Albert Nasibulin

Publications and source records attributed to Albert Nasibulin.

4 recordsLinked to original sources

arXiv2025

Transfer Learning for Transformer-Based Modeling of Nonlinear Pulse Evolution in Er-Doped Fiber Amplifiers

A neural network model based on the Transformer architecture has been developed to predict the nonlinear evolution of optical pulses in Er-doped fiber amplifier under conditions of limited experimental data. To address data scarcity, a two-stage training strategy is employed. In the first stage, the model is pretrained on a synthetic dataset generated through numerical simulations of the amplifier's nonlinear dynamics. In the second stage, the model is fine-tuned using a small set of experimental measurements. This approach enables accurate reproduction of the fine spectral structure of optical pulses observed in experiments across various nonlinear evolution regimes, including the development of modulational instability and the propagation of high-order solitons.

physics.optics↗

arXiv2025

Unveiling the Puzzle of Brittleness in Single Crystal Iridium

Materials for extreme environments require high strength yet ductile to tolerate catastrophic damage. Face-centered cubic (FCC) metals are typically ductile under stress, but single-crystal FCC iridium exhibits intrinsically brittle, limiting its wider applications. Great efforts on theoretical studies have attributed this to non-planar dislocation cores or impurities, while direct experimental evidence has remained elusive. Here we report that high-density, sessile Frank dislocation loops with zero-net Burgers vectors are the primary cause of the brittleness, identified through atomic-resolution scanning transmission electron microscopy. Through first-principles calculations, supported by discrete dislocation dynamics simulations, we reveal that these loops form via an energetically favorable transformation from mixed perfect dislocations under stress, a process unique to iridium among other FCC metals. The immobile loops act as potent barriers, drastically increasing yield strength and work hardening by impeding dislocation glide and consuming mobile dislocations. These decisive results not only deepen the understanding of the iridium brittleness, but also describe the existence of a new embrittlement mechanism inherent to the FCC lattice and not previously described in the literature. The latter may enable novel routes for property tuning across a broad class of materials, which is of paramount importance to metallurgical technology

cond-mat.mtrl-sci↗

arXiv2025

Influence of oxygen-defects on intraband terahertz conductivity of carbon nanotubes

The exceptional charge transport properties of single-walled carbon nanotubes (SWCNTs) enable numerous ultrafast optoelectronic applications. Modifying SWCNTs by introducing defects significantly impacts the performance of nanotube-based devices, making defect characterization crucial. This research tracked these effects in oxygen plasma-treated SWCNT thin films. Sub-picosecond electric fields of varying strengths and additional photoexcitation were used to assess how defects influence charge carrier transport. Changes in effective conductivity within the terahertz (THz) range were found to be strongly dependent on impurity levels. The plasmon resonance shift to higher THz frequencies aligns with the defect-induced reduction in conductivity and slowed carrier migration within the network. An increase in THz field strength resulted in diminished conductivity due to intraband absorption bleaching. To address the emergence of hot charge carriers, a modified Drude model, which considers non-equilibrium charge carrier distribution via fielddependent scattering rates, was applied. The dominant charge-impurity scattering rate in plasma-treated samples corresponded with an increase in defects. Additionally, the impact of defects on charge carrier dynamics on a picosecond timescale was examined. The modeled plasma-treated SWCNTs wire-grid polarizer for the THz range reveals the potential for multi-level engineering of THz devices to customize properties through controlled defect populations.

cond-mat.mtrl-sci↗

arXiv2019

Ambipolar perovskite light electrochemical cell for transparent display devices

Perovskite light-emitting diodes (PeLEDs) have recently attracted great research luminescence at room temperature in interest for their narrow emissions and solution processability. Remarkable progress has been achieved PeLEDs in recent years. Here we present the new configuration of ambipolar transparent perovskite light emitting device. The combination of voltage induced p-i-n formation and ionically doped carbon electrodes and allows electroluminescence in forward and reverse bias. Here we present easy-to-do transparent ambipolar light emitting subpixel based on inorganic perovskite and single wall carbon nanotubes. For this experiment PeLEDs were assembled using a glass substrate with ITO stripes as bottom electrode; spin-coated CsPbBr3/I3:PEO composite as emissive layer; single wall carbon nanotubes deposited by a simple press transfer process at room temperature. We demonstrate a concept of stacked multicolor tandem pixel. Stack of transparent light emitting units might allow fine color tuning in parallel tandem connection without segregation compared to mixed halide perovskites. This configuration conforms pixel downsizing and make to fabrication of emissive multijunction pixels in a stack.

physics.app-ph↗