Phase locking of two fiber lasers is demonstrated experimentally by the use of a self-imaging resonator with a spatial filter. The high-contrast interference strips of the coherent beam profile are observed. The coherent output power of the fiber array exceeds 12W and the efficiency of coherent power combination is 88% with pump power of 60W. The whole system operates quite stably and, for the spatial filter, no thermal effects have been observed, which means that we can increase the coherent output power further by this method.
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http://dx.doi.org/10.1364/oe.14.002721 | DOI Listing |
Micromachines (Basel)
January 2025
Department of Electrical and Computer Engineering, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
This paper presents, for the first time, a rotary actuator functionalized by an inclined disc rotor that serves as a distal optical scanner for endoscopic probes, enabling side-viewing endoscopy in luminal organs using different imaging/analytic modalities such as optical coherence tomography and Raman spectroscopy. This scanner uses a magnetic rotor designed to have a mirror surface on its backside, being electromagnetically driven to roll around the cone-shaped hollow base to create a motion just like a precessing coin. An optical probing beam directed from the probe's optic fiber is passed through the hollow cone to be incident and bent on the back mirror of the rotating inclined rotor, circulating the probing beam around the scanner for full 360° sideway imaging.
View Article and Find Full Text PDFRev Sci Instrum
January 2025
National Key Laboratory of Science and Technology on Advanced Laser and High Power Microwave, Institute of Applied Electronics, China Academy of Engineering Physics, Mianyang 621900, China.
The Chinese Academy of Engineering Physics Terahertz Free Electron Laser Facility (CAEP THz FEL, CTFEL) has been operated as a user facility for over five years. To further meet the growing demands of modern science, an upgrade project for an infrared-terahertz free electron laser facility based on CTFEL has been proposed to broaden the frequency range from 0.1-4.
View Article and Find Full Text PDFNanomaterials (Basel)
January 2025
School of Physics and Optoelectronics, South China University of Technology, Guangzhou 510640, China.
Artificial microstructures, especially metamaterials, have garnered increasing attention in numerous applications due to their rich and distinctive properties. Starting from the principle of multi-beam interference, we have theoretically devised a beam configuration consisting of six symmetrically distributed coherent beams to generate two-dimensional microstructures with diverse shapes of unitcells under different polarization combinations. In particular, a split-ring metamaterial template is achieved with two adjacent circularly and four linearly polarized beams with such single-step holographic interferometry.
View Article and Find Full Text PDFStruct Dyn
January 2025
Center for Free-Electron Laser Science CFEL, Deutsches Elektronen-Synchrotron DESY, Notkestr. 85, 22607 Hamburg, Germany.
Sub-ångström spatial resolution of electron density coupled with sub-femtosecond to few-femtosecond temporal resolution is required to directly observe the dynamics of the electronic structure of a molecule after photoinitiation or some other ultrafast perturbation, such as by soft X-rays. Meeting this challenge, pushing the field of quantum crystallography to attosecond timescales, would bring insights into how the electronic and nuclear degrees of freedom couple, enable the study of quantum coherences involved in molecular dynamics, and ultimately enable these dynamics to be controlled. Here, we propose to reach this realm by employing convergent-beam x-ray crystallography with high-power attosecond pulses from a hard-x-ray free-electron laser.
View Article and Find Full Text PDFWe derive the Goos-Hänchen (GH) and Imbert-Fedorov (IF) shifts of random electromagnetic beams with arbitrary state and degree of polarization and spatial coherence. Further, we demonstrate the general formalism by calculating analytic expressions for the GH and IF shifts of an electromagnetic Gaussian Schell-model (EGSM) beam and show that the GH shifts may exist irrespective of the degree and state of polarization of the beam, while the IF shifts vanish when the beam is either s or p polarized or completely unpolarized. In addition, the spatial coherence width of the EGSM beam is found to influence only the angular GH and IF shifts.
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