A model of a superradiant laser comprising of N three-level systems driven by two pumping lasers is considered in semiclassical approximation. Steady-state equations for density matrix elements are solved both analytically and numerically. Various properties of generated light are investigated. It is found that such a laser can exhibit both superradiance, when the intensity scales as N(2), and subradiance when the intensity does not depend on N. The phase of the laser field is locked to the relative phase of the pumping lasers.
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http://dx.doi.org/10.1364/OL.36.002779 | DOI Listing |
Adv Skin Wound Care
January 2025
Keith Gordon Harding, Mb ChB, CBE, FRCGP, FRCP, FRCS, FLSW, is Professor Emeritus Cardiff University, Cardiff, Wales; Adjunct Professor Monash University Malaysia, Subang Jaya, Selangor, Malaysia; and Co-Founder and Editor in Chief of the International Wound Journal. Melissa Blow, BSc, is Principal Podiatrist, South East Wales Vascular Network, Aneurin Bevan University Health Board, Cardiff, Wales. Faye Ashton, BSc, is Vascular Research Nurse, Leicester Biomedical Research Centre, Glenfield University Hospital, Leicester, United Kingdom. David Bosanquet, MD, is Consultant Vascular Surgeon, South East Wales Vascular Network, Aneurin Bevan University Health Board. Acknowledgments: The authors acknowledge the assistance of Firstkind Ltd, Hawk House, Peregrine Business Park, Gomm Road, High Wycombe, United Kingdom HP13 7DL for sponsoring the study (grant ref: FSK-SPECKLE-001) and provided the NMES devices for the trial. Keith Harding has received payments for consulting work from Firstkind Ltd. The authors have disclosed no other financial relationships related to this article. Submitted November 28, 2023; accepted in revised form April 17, 2024.
Objective: To determine if intermittent neuromuscular electrostimulation (NMES) of the common peroneal nerve increases microvascular flow and pulsatility in and around the wound bed of patients with combined venous and arterial etiology.
Methods: Seven consenting participants presenting with mixed etiology leg ulcers participated in this study. Microvascular flow and pulsatility was measured in the wound bed and in the skin surrounding the wound using laser speckle contrast imaging.
Natl Sci Rev
February 2025
Institute of Nanoscience and Applications, Department of Electrical and Electronic Engineering, Southern University of Science and Technology, Shenzhen 518055, China.
Colloidal quantum dots (QDs) are solution-processable semiconductor nanocrystals with favorable optoelectronic characteristics, one of which is their multi-excitonic behavior that enables broadband polychromatic light generation and amplification from monodisperse QDs. However, the practicality of this has been limited by the difficulty in achieving spatial separation and patterning of different colors as well as the high pumping intensity required to excite the multi-excitonic states. Here, we have addressed these issues by integrating monodisperse QDs in multi-excitonic states into a specially designed cavity, in which the QDs exhibit an anisotropic polychromatic emission (APE) characteristic that allows for tuning the emission from green to red by shifting the observation direction from perpendicular to lateral.
View Article and Find Full Text PDFAdv Mater
January 2025
State Key Laboratory of Low-Dimensional Quantum Physics and Department of Physics, Tsinghua University, Beijing, 100084, P.R. China.
Over the past decade, semiconducting halide perovskite lasers have emerged as a transformative platform in optoelectronics, owing to unique properties such as high photoluminescence quantum yields, tunable bandgaps, and low-cost fabrication processes. This review systematically examines the advancements in halide perovskite lasers, covering diverse laser architectures, such as whispering gallery mode, Fabry-Pérot, plasmonic, bound states in the continuum (BIC), quantum dot, and polariton lasers. The mechanisms of optical gain, the role of material engineering in optimizing lasing performance, and the challenges associated with continuous-wave (CW) pumping and electrically driven lasing are discussed.
View Article and Find Full Text PDFNat Commun
January 2025
Humboldt Centre for Nano- and Biophotonics, Institute for Light and Matter, Department of Chemistry and Biochemistry, University of Cologne, Köln, Germany.
Non-linearities in organic exciton-polariton microcavities represent an attractive platform for quantum devices. However, progress in this area hinges on the development of material platforms for high-performance polariton lasing, scalable and sustainable fabrication, and ultimately strategies for electrical pumping. Here, we show how introducing Schlieren texturing and a rough intra-cavity topography in a liquid crystalline conjugated polymer enables strong in-plane confinement of polaritons and drastic enhancement of the lasing properties.
View Article and Find Full Text PDFWe report lasing action in a femtosecond-laser-inscribed waveguide in thulium-doped barium-gallium-germanium oxide (BGG) glass. A laser cavity was assembled with this waveguide that provided a single-mode output of 62 mW when pumped at 1.6 µm.
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