The properties of microscopic semiconductor lasers with external optical feedback are theoretically analysed. The size-dependence of the critical feedback level, at which the laser first becomes unstable, is clarified, showing how the dominant indicator of feedback stability is the gain of the laser, irrespective of size. The impact of increased spontaneous emission β-factors and over-damped operation is evaluated, exposing a diminished phase sensitivity of microscopic lasers, and a trade-off between modulation bandwidth and feedback stability is identified.
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http://dx.doi.org/10.1364/OE.417869 | DOI Listing |
Lasers Med Sci
January 2025
Centro Universitário do Estado do Pará, Belém, Brazil.
The present study investigates the potential contribution of Photobiomodulation (PBM) to the regeneration of the bone following the extraction of the first mandibular molar in rats. The study evaluates the efficacy of PBM, using both Low-Level Laser Therapy (LLLT) and Light-Emitting Diode Therapy (LEDT), as promotors of osteoblastic activity and the formation of new bone. Study design, setting, and sample: 45 male Wistar rats were divided randomly into three groups of 15 individuals - (i) control group (left lower molar removed only), (ii) the LLL group (molar removed, followed by LLLT), and (iii) the LED group (molar removed, followed by LEDT).
View Article and Find Full Text PDFJ Mol Graph Model
January 2025
Institute of Chemical Physics after A.B. Nalbandyan of NAS RA, 5/2 P. Sevak St., Yerevan, 0014, Armenia.
Liquid crystals (LC) are widely used in various optical devices due to their birefringence, dielectric anisotropy, and responsive behavior to external fields. Enhancing the properties of existing LCs through doping with nanoparticles, including semiconductor quantum dots, offers a promising route for improving their performance. Among various nanoparticles, QDs stand out for their high charge mobility, sensitivity in the near-infrared spectral region, and cost-effectiveness.
View Article and Find Full Text PDFJ Phys Chem Lett
January 2025
School of Physics, State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China, Chengdu 611731, China.
Ultrashort laser pulses are extensively used for efficient manipulation of interfacial spin injection in two-dimensional van der Waals (vdW) heterostructures. However, physical processes accompanying the photoinduced spin transfer dynamics on the all-semiconductor ferromagnetic vdW heterostructure remain largely unexplored. Here, we present a computational investigation of the femtosecond laser pulse induced purely electron-mediated spin transfer dynamics at a time scale of less than 50 fs in a vdW heterostructure.
View Article and Find Full Text PDFMicrosc Microanal
January 2025
Department of Materials Science and Engineering, McMaster University, Hamilton, Ontario L8S 4L7, Canada.
Atom probe tomography (APT) enables three-dimensional chemical mapping with near-atomic scale resolution. However, this method requires precise sample preparation, which is typically achieved using a focused ion beam (FIB) microscope. As the ion beam induces some degree of damage to the sample, it is necessary to apply a protective layer over the region of interest (ROI).
View Article and Find Full Text PDFMicrosc Microanal
January 2025
Université de Lorraine, CNRS, Arts et Métiers, LEM3, Metz 57070, France.
Characterizing threading dislocations (TDs) in gallium nitride (GaN) semiconductors is crucial for ensuring the reliability of semiconductor devices. The current research addresses this issue by combining two techniques using a scanning electron microscope, namely electron channeling contrast imaging (ECCI) and high-resolution electron backscattered diffraction (HR-EBSD). It is a comparative study of these techniques to underscore how they perform in the evaluation of TD densities in GaN epitaxial layers.
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