In this work, direct irradiation by a Ti:Sapphire (100 fs) femtosecond laser beam at third harmonic (266 nm), with a moderate repetition rate (50 and 1000 Hz), was used to create regular periodic nanostructures upon polystyrene (PS) thin films. Typical Low Spatial Frequency LIPSSs (LSFLs) were obtained for 50 Hz, as well as for 1 kHz, in cases of one spot zone, and also using a line scanning irradiation. Laser beam fluence, repetition rate, number of pulses (or irradiation time), and scan velocity were optimized to lead to the formation of various periodic nanostructures. It was found that the surface morphology of PS strongly depends on the accumulation of a high number of pulses (10 to 10 pulses) at low energy (1 to 20 µJ/pulse). Additionally, heating the substrate from room temperature up to 97 °C during the laser irradiation modified the ripples' morphology, particularly their amplitude enhancement from 12 nm (RT) to 20 nm. Scanning electron microscopy and atomic force microscopy were used to image the morphological features of the surface structures. Laser-beam scanning at a chosen speed allowed for the generation of well-resolved ripples on the polymer film and homogeneity over a large area.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8143183 | PMC |
| http://dx.doi.org/10.3390/nano11051060 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Measuring age-dependent viscoelasticity of organelles, cells and organisms with time-shared optical tweezer microrheology.
Nat Nanotechnol
January 2025
ICFO-Institut de Ciències Fotòniques, Castelldefels, The Barcelona Institute of Science and Technology, Barcelona, Spain.
Quantifying the mechanical response of the biological milieu (such as the cell's interior) and complex fluids (such as biomolecular condensates) would enable a better understanding of cellular differentiation and aging and accelerate drug discovery. Here we present time-shared optical tweezer microrheology to determine the frequency- and age-dependent viscoelastic properties of biological materials. Our approach involves splitting a single laser beam into two near-instantaneous time-shared optical traps to carry out simultaneous force and displacement measurements and quantify the mechanical properties ranging from millipascals to kilopascals across five decades of frequency.
View Article and Find Full Text PDFAll-electrical recursive generation and time-domain mode division multiplexing of Hermite-Gaussian pulses for optical, THz and RF links.
Sci Rep
January 2025
THz-Photonics Group, Institut für Hochfrequenztechnik, Technische Universität Braunschweig, 38106, Braunschweig, Germany.
Space division multiplexing (SDM) with Hermite Gaussian (HG) modes, for instance, can significantly boost the transmission link capacity. However, SDM is not suitable in existing single mode fiber networks, and in long-distance wireless, microwave, THz or optical links, the far-field beam distribution may present a problem. Recently it has been demonstrated, that time domain HG modes can be employed to enhance the link capacity.
View Article and Find Full Text PDFSub-2W tunable laser based on silicon photonics power amplifier.
Light Sci Appl
January 2025
Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Hamburg, Germany.
High-power tunable lasers are intensely pursued due to their vast application potential such as in telecom, ranging, and molecular sensing. Integrated photonics, however, is usually considered not suitable for high-power applications mainly due to its small size which limits the energy storage capacity and, therefore, the output power. In the late 90s, to improve the beam quality and increase the stored energy, large-mode-area (LMA) fibers were introduced in which the optical mode area is substantially large.
View Article and Find Full Text PDFGiant Photogalvanic Effect-Induced Terahertz Wave Emission in Wafer-Scale Type-II Dirac Semimetal PtTe.
ACS Appl Mater Interfaces
January 2025
State Key Laboratory of Optoelectronic Materials and Technologies, School of Materials Science and Engineering, Sun Yat-sen University, Guangzhou 510275, P. R. China.
Terahertz (THz) emission arising from the second-order nonlinear photocurrent effects in two-dimensional quantum materials has attracted significant attention due to its high efficiency and ease of polarization manipulation. However, in centrosymmetric quantum materials, the terahertz emission is typically suppressed, caused by the directional symmetry of the photocurrent generated under femtosecond laser excitation. In this work, we report that wafer-scale type-II Dirac semimetal PtTe with lattice centrosymmetry exhibits remarkably high THz emission efficiency (2 orders of magnitude greater than that of a ZnTe nonlinear crystal with equivalent thickness) and pronounced polarization sensitivity at room temperature.
View Article and Find Full Text PDFHelical Surface Relief Formation by Two-Photon Polymerization Reaction Using a Femtosecond Optical Vortex Beam.
J Phys Chem Lett
December 2024
Department of Chemistry, Graduate School of Science, Osaka Metropolitan University, 3-3-138 Sugimoto, Sumiyoshi-ku, Osaka 558-8585, Japan.
Optical vortices possess a helical phase wavefront with central phase dislocation and orbital angular momentum. We demonstrated three-dimensional microstructure formation using a femtosecond optical vortex beam. Two-photon polymerization of photocurable resin was induced by long-term exposure, resulting in the fabrication of cylindrical structures.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!