We experimentally and numerically investigate femtosecond-pulse propagation in a microstructured optical fiber consisting of a silica core surrounded by airholes that are filled with a high-index fluid. This fiber combines the resonant properties of hollow-core bandgap fibers and the high nonlinearity of index-guiding waveguides. A range of nonlinear optical effects can be observed, including soliton propagation, dispersive wave generation, and a Raman self-frequency shift. Tuning the center wavelength of the laser and varying the refractive index of the fluid lead to different propagation effects, mediated by the strongly wavelength-dependent group-velocity dispersion in these photonic bandgap confining structures.
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http://dx.doi.org/10.1364/ol.30.000830 | DOI Listing |
Phys Eng Sci Med
January 2025
School of Biological Science and Medical Engineering, Beihang University, 37 Xueyuan Road, Haidian District, Beijing, 100191, China.
Extracorporeal shock wave therapy (ESWT) achieves its therapeutic purpose mainly through the biological effects produced by the interaction of shock waves with tissues, and the accurate measurement and calculation of the mechanical parameters of shock waves in tissues are of great significance in formulating the therapeutic strategy and evaluating the therapeutic effect. This study utilizes the approach of implanting flexible polyvinylidene fluoride (PVDF) vibration sensors inside the tissue-mimicking phantom of various thicknesses to capture waveforms at different depths during the impact process in real time. Parameters including positive and negative pressure changes (P, P), pulse wave rise time ([Formula: see text]), and energy flux density (EFD) are calculated, and frequency spectrum analysis of the waveforms is conducted.
View Article and Find Full Text PDFJ Opt Soc Am A Opt Image Sci Vis
August 2024
Topological edge states (TESs) and topological corner states (TCSs) in photonic crystals (PCs) provide an effective way to control the propagation and localization of light. The topological performance of integrated photonic devices can be improved by introducing the basic structural unit of photonic quasicrystals (PQCs) into PCs. However, the previous works arranged the basic structural unit of Stampfli-type and 12-fold Penrose-type photonic quasicrystals into triangular lattices, which have a complex structure and allow light to only propagate around 60° or 120° corners, limiting their applications.
View Article and Find Full Text PDFJ Opt Soc Am A Opt Image Sci Vis
August 2024
In this paper, a new theoretical model of a partially coherent Laguerre-Gaussian (LG) beam carrying multiple off-axis vortex phases was established. The evolution properties of the focused intensity of the beam after passing through a thin lens were theoretically studied, and then the modulation effect of multiple off-axis vortex phases on the beam with multiring structured intensity was explored. The results indicate that the multiple off-axis vortex phases can reconstruct the multiring structured intensity within the LG beam, thus generating a structured intensity with multilobe and multiring patterns.
View Article and Find Full Text PDFJ Bacteriol
January 2025
Department of Plant & Microbial Biology, University of California Berkeley, Berkeley, California, USA.
Bacteria encounter chemically similar nutrients in their environment, which impact their growth in distinct ways. Among such nutrients are cobamides, the structurally diverse family of cofactors related to vitamin B (cobalamin), which function as cofactors for diverse metabolic processes. Given that different environments contain varying abundances of different cobamides, bacteria are likely to encounter cobamides that enable them to grow robustly and also those that do not function efficiently for their metabolism.
View Article and Find Full Text PDFJ Dent Sci
January 2025
Department of Dentistry, School of Dentistry, College of Medicine, National Taiwan University, Taipei, Taiwan.
Background/purpose: Studies have demonstrated a relation between hypercholesterolemia and development of apical periodontitis (AP), but the underlying mechanism is uncertain. 27-hydroxycholesterol (27HC), produced by cytochrome P450 27A1 (CYP27A1)-catalyzed hydroxylation of cholesterol, is known to possess pro-inflammatory activity. Felodipine is an anti-hypertensive agent able to inhibit CYP27A1.
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