The gain properties of an oscillator strongly affect its behavior. When the gain is homogeneous, different modes compete for gain resources in a 'winner takes all' manner, whereas with inhomogeneous gain, modes can coexist if they utilize different gain resources. We demonstrate precise control over the mode competition in a mode locked Ti:sapphire oscillator by manipulation and spectral shaping of the gain properties, thus steering the competition towards a desired, otherwise inaccessible, oscillation. Specifically, by adding a small amount of spectrally shaped inhomogeneous gain to the standard homogeneous gain oscillator, we selectively enhance a desired two-color oscillation, which is inherently unstable to mode competition and could not exist in a purely homogeneous gain oscillator. By tuning the parameters of the additional inhomogeneous gain we flexibly control the center wavelengths, relative intensities and widths of the two colors.
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http://dx.doi.org/10.1364/OE.20.009991 | DOI Listing |
J Phys Condens Matter
December 2024
Theoretische Physik II, Physikalisches Institut, Universität Bayreuth, D-95447 Bayreuth, Germany.
We give an introductory account of the recent hyperdensity functional theory for the equilibrium statistical mechanics of soft matter systems (Sammüller2024098201). Hyperdensity functionals give access to the behaviour of arbitrary thermal observables in spatially inhomogeneous equilibrium many-body systems. The approach is based on classical density functional theory applied to an extended ensemble using standard functional techniques.
View Article and Find Full Text PDFPhys Rev Lett
October 2024
Joint Quantum Institute, Department of Physics, University of Maryland, College Park, Maryland 20742, USA.
This Letter presents a theory of interaction-induced band-flattening in strongly correlated electron systems. We begin by illustrating an inherent connection between flat bands and index theorems, and presenting a generic prescription for constructing flat bands by periodically repeating local Hamiltonians with topological zero modes. Specifically, we demonstrate that a Dirac particle in an external, spatially periodic magnetic field can be cast in this form.
View Article and Find Full Text PDFSpectrochim Acta A Mol Biomol Spectrosc
February 2025
Rare Earth College, Jiangxi University of Science and Technology, Ganzhou, Jiangxi 341000, China; National Rare Earth Functional Material Innovation Center, Ganzhou, Jiangxi 341000, China; Key Laboratory of Rare Earths, Chinese Academy of Sciences, Ganzhou, Jiangxi Province 341119, China. Electronic address:
Er-doped glasses and fibers with broadband near infrared (NIR) emission have been widely applied in EDFA. Limited by optical gain band of Er-doped glasses and fibers, it was hardly meet to the demands of broadband amplification in the C + L band. In this work, six glass matrixes were employed for discussing the influence of glass matrix on the Stark splitting of Er and the wavelength of laser output and amplification.
View Article and Find Full Text PDFNat Commun
August 2024
School of Electrical and Electronics Engineering, Nanyang Technological University, Singapore, Singapore.
The nucleolus, a recognized biomolecular condensate, serves as the hub for ribosome biogenesis within the cell nucleus. Its quantity and morphology are discernible indicators of cellular functional states. However, precise identification and quantification of nucleoli remain challenging without specific labeling, particularly for suspended cells, tissue-level analysis and high-throughput applications.
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