arXiv subjects

Albert G. Nasibulin

Publications and source records attributed to Albert G. Nasibulin.

At least 19 recordsLinked to original sources

arXiv2026

Harnessing Evanescent Wave Interaction for Enhanced Optical NO2 Detection with Carbon Nanotube-Coated Side-Polished Fiber

Evanescent-wave photonic sensors employing nanomaterial-coated waveguides are commonly interpreted in terms of absorption modulation of the sensing layer. Here, we demonstrate that, in such systems, gas-induced reshaping of the guided optical mode can dominate the transduction mechanism and even reverse the sign of the optical response. Using side-polished optical fibers covered with single-walled carbon nanotube (SWCNT) thin films, we observe a pronounced polarization- and thickness-dependent response to NO2 exposure. For transverse electric polarization, the optical response decreases with increasing film thickness and changes sign for thicker coatings, whereas for transverse-magnetic polarization, the response increases monotonically. Numerical modeling reveals that modulation of the SWCNT complex refractive index redistributes the evanescent field, alters the mode-matter overlap integral, and controls propagation loss. These results demonstrate that evanescent-wave sensor behavior is governed not only by intrinsic material sensitivity but also by mode reshaping induced by nanomaterial coatings. The identified mechanism provides a general framework for designing fiber-optic and integrated photonic sensors based on evanescent-field interactions with tunable nanomaterials.

physics.optics↗

arXiv2025

Microring resonator as a Rayleigh mirror for broadband laser-cavity comb generation

High-quality microring resonators (MRRs) have proven to be promising sources of optical combs generated from continuous-wave radiation. In addition to the primary comb that propagates along with the pump, Rayleigh scattering creates a comb that travels in the opposite direction. Normally, the scattering is a very weak, however, in the high-quality-factor MRR the power transferred to the backward-propagating comb can be quite significant. We demonstrate that the backward-propagating comb can be used as a feedback source for a fiber laser, effectively creating a nonlinear mirror for the laser cavity. By assembling a simple laser cavity comprising only active fiber and two mirrors, one of which is an integrated MRR, we show a robust self-starting comb generation with width exceeding 500 nm. We confirm the universal character of this approach for other types of microresonators, including whispering gallery mode resonators, by launching self-starting laser cavity combs with the crystalline toroidal cavity, coupled with a tapered fiber. This method provides significant simplification for the filter-driven laser cavity soliton generation, especially when free-space coupling is applied.

physics.optics↗

arXiv2025

Non-epitaxial perovskite polariton laser diode operating under direct current

Reaching lasing in electrically pumped microdevices based on solution-processed semiconductors poses a major scientific and technological challenge. Halide perovskites offer a promising platform for electrical injection, since their optically excited single-crystal cavities and predesigned or postprocessed microstructures have exhibited low lasing threshold. Indirect electrical pumping of a dual-cavity perovskite laser was recently obtained, utilizing a well-established technological concept of embedding a high-luminosity light-emitting diode (LED) with a high-gain medium into an integrated device. Direct charge-carrier injection into a perovskite LED excited by auxiliary short-, optical-pulses resulted into amplified spontaneous emission. Other efforts for rational engineering of architectures that allow for high charge-carrier density are still to demonstrate lasing. Here, we develop a novel strategy for achieving direct electrical pumping of a perovskite laser. We integrate a solution-grown CsPbBr3 microplate with chemically inert single-walled carbon nanotube electrodes and embed them into an optical microcavity. By cooling the microdevice down to 8 K at a constant current, a perovskite p-i-n diode is formed that facilitates a balanced carrier injection at high current densities. The perovskite microcavity diode operates in the strong coupling regime, exhibiting polariton lasing under a direct current of 65 uA.

physics.optics↗

arXiv2025

Biorealistic Response in Optoelectrically-Driven Flexible Halide-Perovskite Single-Crystal Memristors

The transition to smart wearable and flexible optoelectronic devices communicating with each other and performing neuromorphic computing at the edge is a big goal in next-generation optoelectronics. These devices should perform their regular tasks supported by energy-efficient in-memory calculations. Here, we study the response of the CsPbBr$_3$ halide-perovskite single crystal fabricated on the flexible polymer substrate and integrated with the single-walled carbon nanotube thin film electrodes in a lateral geometry. We show both photodetection functions combined with the synaptic functionality in our device under the application of hybrid optoelectrical stimuli. Furthermore, we demonstrate that our device exhibits frequency-dependent bidirectional modification of synaptic weight with a sliding threshold similar to biologically plausible Bienenstock-Cooper-Munro learning. The demonstrated optoelectronic synaptic behavior in halide-perovskite single-crystals opens the opportunity for the development of hybrid organic-inorganic artificial visual systems.

cond-mat.mtrl-sci↗

arXiv2025

Q-switched Mode-locking in Er-doped ZBLAN Fibre Lasers using Carbon Nanotube Saturable Absorber and GaSb-based SESAM

Mid-infrared fibre lasers are crucial for applications in spectroscopy, medical diagnostics, and environmental sensing, owing to their ability to interact with fundamental molecular vibrational bands. However, achieving stable ultrafast pulse generation in this spectral range remains challenging due to the limited availability of robust saturable absorbers. For the first time, we demonstrate Q-switched mode-locking in an all-fibre Er-doped ZBLAN laser employing an aerosol-synthesised carbon nanotube film. Furthermore, we compare the laser performance with pulse generation using a state-of-the-art GaSb-based SESAM in an identical cavity design. The carbon nanotube saturable absorber enables pulse generation with a minimum duration of 1.32 us and a pulse energy of 1.4 uJ at an average output power of 63.1 mW. In contrast, the SESAM-based laser produces 560-ns pulses with a pulse energy reaching 4.42 uJ and an average power of 138 mW. These results provide new insights into the interplay between saturable absorber properties and mid-IR fibre laser performance, paving the way for next-generation compact ultrafast sources for scientific and industrial applications.

physics.optics↗

arXiv2023

Atomistic mechanism of friction force independence on the normal load and other friction laws for dynamic structural superlubricity

We explore dynamic structural superlubricity for the case of a relatively large contact area, where the friction force is proportional to the area (exceeding $\sim 100\,nm^2$) experimentally, numerically, and theoretically. We use a setup comprised of two molecular smooth incommensurate surfaces -- graphene-covered tip and substrate. The experiments and MD simulations demonstrate independence of the friction force on the normal load, for a wide range of normal loads and relative surface velocities. We propose an atomistic mechanism of this phenomenon, associated with synchronic out-of-plane surface fluctuations of thermal origin, and confirm it by numerical experiments. Based on this mechanism, we develop a theory for this type of superlubricity and show that friction force increases linearly with increasing temperature and relative velocity, for velocities, larger than a threshold velocity. The MD results are in a fair agreement with predictions of the theory.

physics.comp-ph↗

arXiv2023

Inverted loss engineering in functional material covered waveguides

Optical waveguides, covered with thin films, which transmittance can be controlled by external action, are widely used in various applications from optical modulators to saturable absorbers. It is natural to suggest that the waveguide losses will be proportional to the covering material absorption. We demonstrate that under certain conditions this simple assumption fails. Instead, we observe the reduction of the film material absorption can lead to an increase in the waveguide propagation losses. For this, we use a side polished fiber covered with a single-walled carbon nanotube thin film whose absorption is attenuated either due to saturable absorption or electrochemical gating. For the films thicker than 50 nm, we observe saturable absorption to turn into light induced absorption with nonmonotonic dependence on the incident power. With a numerical simulation and analytical approach, we identify that this nontrivial behavior comes from mode reshaping and predict required parameters for its observation.

physics.optics↗

arXiv2023

Nd-Doped Polarization Maintaining All-Fiber Laser With Dissipative Soliton Resonance Mode-Locking at 905 nm

Moving the fiber laser emission to the region below one micron may provide a cheaper, more compact and robust alternatives to the existing solid state lasers. Here, for the first time we report a neodymium mode-locked fiber laser emitting at 905 nm in the all-fiber polarization maintaining configuration. We obtain a self-starting pulse generation in nonlinear amplifying loop mirror (NALM) cavity configuration. To suppress a dominant emission at 1064 nm corresponding to a 4-level laser scheme, we use an active fiber - 920/1064 division multiplexer - active fiber sandwich-like sequence in the NALM loop. A rectangular shape dissipative soliton had nJ energy, 30 pm spectral width and 80 - 430 ps width linearly depending on the pump power. Excellent agreement with numerical simulation allowed us to recover pulse shape and width for the pulses out of autocorrelation window.

physics.optics↗

arXiv2023

Dispersion Managed Mode-locking in all-fiber Polarization-maintaining Nd-doped Laser at 920 nm

We present a comprehensive study of dispersion managed ultrashort-pulse generation in Nd-doped polarization maintaining all-fiber laser at a 920 nm wavelength. We implement a linear laser scheme with a chirped fiber Bragg grating (CFBG) serving as a semitransparent mirror and semiconductor saturable absorber mirror (SESAM) as a mode-locker and as a second non-transparent mirror. Complete 1064 nm emission filtering is ensured by 920/1064 wavelength division multiplexer. The dispersion compensation by CFBG was sufficient to reach anomalous net dispersion in the shortest laser scheme allowing us to investigate mode-locking regimes in the -0.05 ps 2 - 0.24 ps 2 net dispersion range by varying the length of the passive fiber. With this approach we demonstrate high order harmonic mode-locking at dispersion closer to zero and large energy span near-parabolic shape single pulse operation in anomalous dispersion regime. The investigation is supported by numerical simulations used to optimize the laser resonator design and to investigate intracavity pulse evolution.

physics.optics↗

arXiv2022

Ultrafast opto-mechanical terahertz modulators based on stretchable carbon nanotube thin films

For terahertz (THz) wave applications, tunable and rapid modulation is highly required. When studied by means of optical pump-terahertz probe spectroscopy, single-walled carbon nanotubes (SWCNTs) thin films demonstrated ultrafast carrier recombination lifetimes with a high relative change in the signal under optical excitation, making them promising candidates for high-speed modulators. Here, combination of SWCNTthin films and stretchable substrates facilitated studies of the SWCNT mechanical properties under strain,and enabled the development of a new type of an opto-mechanical modulator. By applying a certain strain to the SWCNT films, the effective sheet conductance and therefore modulation depth can be fine-tuned to optimize the designed modulator. Modulators exhibited a photoconductivity change of 3-4 orders of magnitude under the strain due to the structural modification in the SWCNT network. Stretching was used to control the THz signal with a modulation depth of around 100 % without strain and 65 % at a high strainoperation of 40 %. The sensitivity of modulators to beam polarisation is also shown, which might also come in handy for the design of a stretchable polariser. Our results give a fundamental grounding for the design of high-sensitivity stretchable devices based on SWCNT films.

cond-mat.mes-hall↗

arXiv2022

Local ultra-densification of single-walled carbon nanotube films: modeling and experiment

Fabrication of nanostructured metasurfaces poses a significant technological and fundamental challenge. Despite developing novel systems that support reversible elongation and distortion, their nanoscale patterning and control of optical properties remain an open problem. Herein we report the atomic force microscope lithography (AFML) application for nanoscale patterning of single-walled carbon nanotube films and the associated reflection coefficient tuning. We present models of bundling reorganization, formed-pattern stability, and energy distribution describing mechanical behavior with mesoscopic distinct element method (MDEM). All observed and calculated phenomena support each other and present a platform for developing AFML patterned optical devices using meshy nanostructured matter.

cond-mat.mtrl-sci↗

arXiv2022

Gentle patterning approaches towards compatibility with bio-organic materials and their environmental aspects

Advances in material science, bio-electronic, and implantable medicine combined with recent requests for eco-friendly materials and technologies inevitably formulate new challenges for nano- and micro-patterning techniques. Overall, the importance of creating micro and nanostructures is motivated by a large manifold of fundamental and applied properties accessible only at the nanoscale. Lithography is a crucial family of fabrication methods to create prototypes and produce devices on an industrial scale. The pure trend in the miniaturization of critical electronic semiconducting components is recently enhanced by implementing bio-organic systems in electronics. So far, significant efforts have been made to find novel lithographic approaches and develop old ones to reach compatibility with delicate bio-organic systems and minimize the impact on the environment. Herein, we briefly review such delicate materials and sophisticated patterning techniques.

cond-mat.mtrl-sci↗

arXiv2021

Highly Efficient Bilateral Doping of Single-Walled Carbon Nanotubes

A boost in the development of flexible and wearable electronics facilitates the design of new materials to be applied as transparent conducting films (TCFs). Although single-walled carbon nanotube (SWCNT) films are the most promising candidates for flexible TCFs, they still do not meet optoelectronic requirements demanded their successful industrial integration. In this study, we proposed and thoroughly investigated a new approach that comprises simultaneous bilateral (outer and inner surfaces) SWCNT doping after their opening by thermal treatment at 400 C under an ambient air atmosphere. Doping by a chloroauric acid (HAuCl$_{4}$) ethanol solution allowed us to achieve the record value of sheet resistance of 31 $\pm$ 4 $Ω$/sq at a transmittance of 90% in the middle of visible spectra (550 nm). The strong p-doping was examined by open-circuit potential (OCP) measurements and confirmed by ab initio calculations demonstrating a downshift of Fermi level around 1 eV for the case of bilateral doping.

cond-mat.mtrl-sci↗

arXiv2020

Densification of Single-Walled Carbon Nanotube Films: Mesoscopic Distinct Element Method Simulations and Experimental Validation

Nanometer thin single-walled carbon nanotube (CNT) films collected from the aerosol chemical deposition reactors have gathered attention for their promising applications. Densification of these pristine films provides an important way to manipulate the mechanical, electronic, and optical properties. To elucidate the underlying microstructural level restructuring, which is ultimately responsible for the change in properties, we perform large scale vector-based mesoscopic distinct element method simulations in conjunction with electron microscopy and spectroscopic ellipsometry characterization of pristine and densified films by drop-cast volatile liquid processing. Matching the microscopy observations, pristine CNT films with finite thickness are modeled as self-assembled CNT networks comprising entangled dendritic bundles with branches extending down to individual CNTs. Simulations of the film under uniaxial compression uncover an ultra-soft densification regime extending to a ~75% strain, which is likely accessible with the surface tensional forces arising from liquid surface tension during the evaporation. When removing the loads, the pre-compressed samples evolve into homogeneously densified films with thickness values depending on both the pre-compression level and the sample microstructure. The significant reduction in thickness, confirmed by our spectroscopic ellipsometry, is attributed to the underlying structural changes occurring at the 100 nm scale, including the zipping of the thinnest dendritic branches.

cond-mat.mtrl-sci↗

arXiv2020

Raman spectroscopy of GaSe and InSe post-transition metal chalcogenides layers

III-VI post-transition metal chalcogenides (InSe and GaSe) are a new class of layered semiconductors, which feature a strong variation of size and type of their band gaps as a function of number of layers (N). Here, we investigate exfoliated layers of InSe and GaSe ranging from bulk crystals down to monolayer, encapsulated in hexagonal boron nitride, using Raman spectroscopy. We present the N-dependence of both intralayer vibrations within each atomic layer, as well as of the interlayer shear and layer breathing modes. A linear chain model can be used to describe the evolution of the peak positions as a function of N, consistent with first principles calculations.

cond-mat.mtrl-sci↗

arXiv2019

Modified silicone rubbers for fabrication and contacting of flexible suspended membranes of n-/p-GaP nanowires with single-walled carbon nanotube transparent contact

This work proposes new chemical and mechanical materials and techniques for III-V semiconductor NW/silicone membrane formation and optoelectronic device fabrication. Molecular beam epitaxy (MBE)-synthesized n-, p- and i-GaP NWs were encapsulated by introduced G-coating method into synthesized polydimethylsiloxane-graft-polystyrene and released from the Si growth substrate. The fabricated membranes were contacted with different materials including single-walled carbon nanotubes or ferrocenyl-containing polymethylhydrosiloxane with and without multi-walled carbon nanotubes doping. The electrical connection of the fabricated membranes was verified by electron beam induced current (EBIC) spectroscopy. The developed methods and materials can be applied for fabrication of high quality flexible inorganic optoelectronic devices.

physics.app-ph↗

arXiv2019

Intersubband plasmon excitations in doped carbon nanotubes

We theoretically investigate intersubband plasmon excitations in doped single wall carbon nanotubes (SWNTs) by examining the dependence of plasmon frequency on the nanotube diameter, chirality, and Fermi energy. The intersubband plasmons can be excited by light with polarization perpendicular to the nanotube axis and thus the plasmon excitations corresponds to optical transitions between the two different subbands, which are sensitive to the Fermi energy. In every SWNT, this mechanism leads to the emergence of the optical absorption peak at the plasmon frequency for a given Fermi energy, $E_F$. The plasmon frequencies calculated for many SWNTs with diameter $d_t < 2$ nm exhibit a dependence on $(1/d_t)^{0.7}$ and the frequencies are further affected by Fermi energy as $E_F^{0.25}$. With this knowledge, it is possible to develop a map of intersubband plasmon excitations in doped SWNTs that could be useful to quickly estimate the doping level and also be an alternative way to characterize nanotube chirality.

cond-mat.mes-hall↗

arXiv2018

Ambient condition production of high quality reduced graphene oxide

Reduced graphene oxide becomes one of the most popular materials for applications in various optical, electronic and sensor devices. Even though many methods have been already reported for reduced graphene oxide synthesis, they usually rise issues related to their efficiency, quality and environmental impact. This work demonstrates a simple, environmentally friendly and effective method for reducing graphene oxide under ambient conditions using nanosecond infrared laser irradiation. As a result, a Raman band intensity ratio of I(G)/I(D) of 4.59 was achieved with an average crystallite size of ~90 nm. This graphene is of higher quality than what can be achieved with most of the existing methods. Additionally, the demonstrated reduction technique allows the selective reduction of graphene oxide and control the amount of functional groups on the surface of the material. Gas sensors fabricated according to the proposed technique efficiently detect NO$_2$, NH$_3$, and H$_2$S with the sensitivity down to 10 ppm.

cond-mat.mtrl-sci↗