arXiv subjects

Mariusz Zdrojek

Publications and source records attributed to Mariusz Zdrojek.

6 recordsLinked to original sources

arXiv2026

Cross-Dimensional Exciton Coupling in Quantum Dot - Carbon Nanotube Hybrid Thin Films

Dipole-dipole interactions provide a route to couple excitons across materials of different dimensionality. Here, we introduce hybrid films as a cross-dimensional excitonic platform and develop a theory of resonant Raman scattering in the presence of dipolar exciton coupling. Combining a coupled-oscillator model with perturbation theory, we show that coupling renormalizes the exciton-photon matrix elements and modifies nanotube Raman excitation profiles. We test this framework in vacuum-filtered films containing InP/ZnS quantum dots and mixed chirality metallic single-walled carbon nanotubes. The quantum-dot exciton remains near 1.83 eV, while chirality-dependent nanotube excitons span 1.7-1.93 eV, enabling systematic control of excitonic detuning. Relative to pristine nanotube films, the hybrids exhibit detuning-dependent redshifts and blueshifts, Raman intensity enhancement, reduced effective linewidths, and near-resonant two-branch profiles. The model yields an effective splitting of approximately 110 meV. Resonant Raman scattering thus provides component-selective access to dipolar interactions that are only weakly apparent in ensemble absorption spectra.

cond-mat.mes-hall↗

arXiv2026

Evanescent absorption spectroscopy of transition metal dichalcogenide materials using guided photoluminescence in Si$_3$N$_4$ photonic waveguides

On-chip integration of two-dimensional transition metal dichalcogenides (TMDs) with photonic waveguides underpins a growing class of compact optoelectronic and sensing devices, whose performance depends on the optical absorption of the 2D material in this integrated environment. We demonstrate source-free, on-chip evanescent absorption spectroscopy of MoS$_2$ and WS$_2$ flakes integrated on Si$_3$N$_4$ waveguides, in which the broadband defect-related photoluminescence of the Si$_3$N$_4$ core itself acts as the internal probe. Light generated inside the core propagates under the TMD flake and is spectrally attenuated by evanescent interaction with the 2D material, and normalizing the transmitted spectrum to a reference waveguide without TMD yields the energy-dependent absorption response without any external illumination. The extracted guided absorption agrees with Raman and local micro-photoluminescence characterization and resolves differences between spatially uniform and non-uniform flakes. A complementary top-pumping scheme recovers guided WS$_2$ photoluminescence, whose spectral reshaping during propagation is quantitatively reproduced by the measured absorption. This source-free platform qualifies 2D materials in their integrated photonic environment and provides a direct route toward waveguide-integrated TMD photodetectors and sensors.

physics.optics↗

arXiv2014

Temperature-dependent nonlinear phonon shifts in a supported MoS2 monolayer

We report Raman spectra measurements on a MoS2 monolayer supported on SiO2 as a function of temperature. Unlike in previous studies, the positions of the two main Raman modes, E2g1 and A1g exhibited nonlinear temperature dependence. Temperature dependence of phonon shifts and widths is explained by optical phonon decay process into two acoustic phonons. On the basis of Raman measurements, local temperature change under laser heating power at different global temperatures is derived. Obtained results contribute to our understanding of the thermal properties of two-dimensional atomic crystals and can help to solve the problem of heat dissipation, which is crucial for use in the next generation of nanoelectronic devices.

cond-mat.mes-hall↗

arXiv2012

Linearly polarized, Q-switched Er-doped fiber laser based on reduced graphene oxide saturable absorber

We demonstrate generation of linearly polarized pulses from a passively Q-switched Erbium-doped fiber laser. The cavity was designed using only polarization maintaining (PM) fibers and components, resulting in linearly polarized output beam with degree of polarization (DOP) at the level of 97.6%. Reduced graphene oxide (rGO) was used as a saturable absorber for Q-switched operation. The laser was capable of delivering 1.85us pulses with 125nJ pulse energy at 115kHz repetition rate.

physics.optics↗

arXiv2012

Graphene Oxide vs. Reduced Graphene Oxide as saturable absorbers for Er-doped passively mode-locked fiber laser

In this work we demonstrate comprehensive studies on graphene oxide (GO) and reduced graphene oxide (rGO) based saturable absorbers (SA) for mode-locking of Er-doped fiber lasers. The paper describes the fabrication process of both saturable absorbers and detailed comparison of their parameters. Our results show, that there is no significant difference in the laser performance between the investigated SA. Both provided stable, mode-locked operation with sub-400 fs soliton pulses and more than 9 nm optical bandwidth at 1560 nm center wavelength. It has been shown that GO might be successfully used as an efficient SA without the need of its reduction to rGO. Taking into account simpler manufacturing technology and the possibility of mass production, GO seems to be a good candidate as a cost-effective material for saturable absorbers for Er-doped fiber lasers.

cond-mat.mtrl-sci↗

arXiv2009

Electric charge enhancements in carbon nanotubes: Theory and experiments

We present a detailed study of the static enhancement effects of electric charges in micron-length single-walled carbon nanotubes, using theoretically an atomic charge-dipole model and experimentally electrostatic force microscopy. We demonstrate that nanotubes exhibit at their ends surprisingly weak charge enhancements which decrease with the nanotube length and increase with the nanotube radius. A quantitative agreement is obtained between theory and experiments.

cond-mat.mes-hall↗