We have studied the effect of a twist defect on the conversion of the fundamental mode (FM) into an optical vortex (OV) in a helical-core fiber (HCF). We have shown that if such a twist defect is situated in the middle of the HCF, which converts the FM into an OV, such a fiber system can continuously change the orbital angular momentum (OAM) of the output field from 0 to 1 (in a.u.). This control of the OAM is achieved by variation of the twist angle. In this action upon the OAM, this system has analogy with the quarter-wave plate, which is able to change the spin angular momentum. We also introduced the generalized Stokes parameters (SPs) and Poincaré sphere to visualize evolution of the superposition of states with zero and nonzero OAM. Connection of SPs with geometric characteristics of the location of singularity is made.
Download full-text PDF |
Source |
---|---|
http://dx.doi.org/10.1364/OL.38.002277 | DOI Listing |
J Biomech
January 2025
Stevens Institute of Technology, Hoboken, NJ, USA. Electronic address:
This study revealed how high school pitchers generated momenta during fastballs and changeups at a whole-body level. Baseball pitchers control ground reaction forces to generate whole-body momentum. Pitchers attempt to throw as fast and accurately as possible during fastballs but also need to throw off-speed pitches like changeups to deceive batters.
View Article and Find Full Text PDFNanomaterials (Basel)
January 2025
Department of Physics and Natural Science Research Institute, University of Seoul, Seoul 02504, Republic of Korea.
Bulk n-type SrTiO (STO) has long been known to possess a superconducting ground state at an exceptionally dilute carrier density. This has raised questions about the applicability of the BCS-Eliashberg paradigm with its underlying adiabatic assumption. However, recent experimental reports have set the pairing gap to the critical temperature (Tc) ratio at the BCS value for superconductivity in Nb-doped STO, even though the adiabaticity condition the BCS pairing requires is satisfied over the entire superconducting dome only by the lowest branch of optical phonons.
View Article and Find Full Text PDFJ Neuroeng Rehabil
January 2025
Department of Mechanical & Aerospace Engineering, University of Florida, Gainesville, FL, USA.
Background: Advanced age brings a loss of plantar sensation, represented, for example, as higher sensation thresholds in standardized testing. This is thought to contribute to an increased risk of falls among older adults - an intuitive premise that has yet to be fully investigated, especially in the context of walking balance. The purpose of this study was to quantify the association between plantar sensation and the instability elicited by a suite of walking balance perturbations that differ in direction and context in a cohort of n = 28 older adults (73.
View Article and Find Full Text PDFClin Biomech (Bristol)
January 2025
Univ. Polytechnique Hauts-de-France, LAMIH, CNRS, UMR 8201, F-59313 Valenciennes, France.
Background: Multiple sclerosis induces locomotor impairments. The objective was to characterize the effects of Multiple Sclerosis on whole-body angular momentum control during gait initiation.
Methods: Fifteen patients with Multiple Sclerosis with Expanded Disability status scale of 2.
Eur Phys J C Part Fields
January 2025
Department of Physics, University of Alberta, Edmonton, AB T6G 2E1 Canada.
We analyze the angular momentum balance for a particle undergoing Thomas precession. The relationships among relativistic torque, the center of mass, and the center of inertia for a spinning particle are clarified. We show that spin precession is accompanied by orbital angular momentum precession, and present examples of the resulting out-of-plane motion.
View Article and Find Full Text PDFEnter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!