Exact closed-form solutions to Maxwell's equations are used to investigate the acceleration of electrons in vacuum driven by ultrashort and nonparaxial radially polarized laser pulses. We show that the threshold power above which significant acceleration takes place is greatly reduced by using a tighter focus. Moreover, electrons accelerated by tightly focused single-cycle laser pulses may reach around 80% of the theoretical energy gain limit, about twice the value previously reported with few-cycle paraxial pulses. Our results demonstrate that the direct acceleration of electrons in vacuum is well within reach of current laser technology.
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http://dx.doi.org/10.1364/OL.37.002442 | DOI Listing |
Lasers Med Sci
January 2025
Cornell University, Ithaca, USA.
Purpose: Photobiomodulation (PBM) is a non-invasive therapeutic procedure that consists of irradiating a local area of the skin with red and near-infrared lasers or light emitting diodes (LEDs). Local PBM has been studied as a method to improve exercise performance and recovery. This review aims to evaluate the efficacy of whole-body PBM for exercise performance and recovery, comparing its findings to the established effects of localized PBM.
View Article and Find Full Text PDFRev Sci Instrum
January 2025
Department of Plasma Physics and Fusion Engineering, University of Science and Technology of China, Hefei 230026, China.
A novel all-fiber optic current sensor (FOCS) is designed specifically for the measurement of large transient currents based on the Faraday effect. A reciprocal symmetric structure is incorporated into the optical sensing loop, and the current dependent phase demodulation is achieved by using a passive optical fiber coupler and the homodyne detection scheme. This design offers several advantages, including structural simplicity, high voltage insulation, low noise, high linearity, and excellent frequency response, and is highly suitable for use in any system of high-voltage, high-power, and high-frequency in nature.
View Article and Find Full Text PDFPhys Rev Lett
December 2024
Stanford University, Department of Mechanical Engineering, Stanford, California 94305, USA.
The extreme electric fields created in high-intensity laser-plasma interactions could generate energetic ions far more compactly than traditional accelerators. Despite this promise, laser-plasma accelerator experiments have been limited to maximum ion energies of ∼100 MeV/nucleon. The central challenge is the low charge-to-mass ratio of ions, which has precluded one of the most successful approaches used for electrons: laser wakefield acceleration.
View Article and Find Full Text PDFNano Lett
January 2025
Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, United States.
Rapid validation of newly predicted materials through autonomous synthesis requires real-time adaptive control methods that exploit physics knowledge, a capability that is lacking in most systems. Here, we demonstrate an approach to enable real-time control of thin film synthesis by combining optical diagnostics with a Bayesian state estimation method. We developed a physical model for film growth and applied the direct filter (DF) method for real-time estimation of nucleation and growth rates during pulsed laser deposition (PLD).
View Article and Find Full Text PDFMicrosc Res Tech
January 2025
Department of Restorative and Prosthetic Dental Sciences, College of Dentistry, Dar Al Uloom University, Riyadh, Saudi Arabia.
Effect of different root canal irrigation regimes microbubble emulsion (MBE) via riboflavin photosensitizer (RFP), cerium oxide (CeO) nanoparticles (NPs), and Nd: YAP laser on antibacterial efficiency, microhardness (MH), smear layer (SL) removal efficacy, and push-out bond strength (PBS) of AH plus sealer to canal dentin. Sixty single-rooted teeth were selected, disinfected, and categorized into four groups based on the type of disinfection. Following disinfection, a pair of samples were randomly selected and visualized under scanning electron microscope (SEM) for SL evaluation.
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