Spectroscopic ellipsometry (SE) characterization of layered transition metal dichalcogenide (TMD) thin films grown by vapor phase sulfurization is reported. By developing an optical dispersion model, the extinction coefficient and refractive index, as well as the thickness of molybdenum disulfide (MoS₂) films, were extracted. In addition, the optical band gap was obtained from SE and showed a clear dependence on the MoS₂ film thickness, with thinner films having a larger band gap energy. These results are consistent with theory and observations made on MoS₂ flakes prepared by exfoliation, showing the viability of vapor phase derived TMDs for optical applications.

In this paper, we establish connections between the thresholds and mechanisms of the damage and white-light generation upon femtosecond laser irradiation of wide-bandgap transparent materials. On the example of Corning Willow glass, evolution of ablation craters, their quality, and white-light emission were studied experimentally for 130-fs, 800-nm laser pulses. The experimental results indicate co-existence of several ablation mechanisms which can be separated in time. Suppression of the phase explosion mechanism of ablation was revealed at the middle of the irradiation spots. At high laser fluences, air ionization was found to strongly influence ablation rate and quality and the main mechanisms of the influence are analysed. To gain insight into the processes triggered by laser radiation in glass, numerical simulations have been performed with accounting for the balance of laser energy absorption and its distribution/redistribution in the sample, including bremsstrahlung emission from excited free-electron plasma. The simulations have shown an insignificant role of avalanche ionization at such short durations of laser pulses while pointing to high average energy of electrons up to several dozens of eV. At multi-pulse ablation regimes, improvement of crater quality was found as compared to single/few pulses.

Laser treatment of amorphous TiO ₂ nanotube layers leads to their crystallization without deformation or formation of the thermal oxide layer.

Controlling the spatial distribution of functional groups on 2D materials on a micrometer scale and below represents a fascinating opportunity to achieve anisotropic (opto)electronic properties of these materials. Periodic patterns of covalent functionalization can lead to periodic potentials in the monolayer; however, creating such superstructures is very challenging. Here, we describe an original approach to the periodic functionalization of graphene induced by substrate patterning using a pulsed laser. Laser-induced periodic surface structures (LIPSS) are produced on silicon wafers with thermally-grown oxide layers. The irradiation conditions for the formation of LIPSS confined at the SiO₂/Si interface have been unravelled. LIPSS imprint their periodicity to the reactivity of the monolayer graphene placed on the substrate via modulation of its local doping level. This method is clean, straightforward and scalable with high spatial resolution.