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The evolution of Er clusters in CaF crystals has not been fully understood, making the underlying mechanism for regulating the upconversion luminescence color of Er:CaF crystals remains unclear. In this work, the first-principles calculation is combined with the synchrotron X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), as well as the dielectric spectra and absorption spectra to study the Er-doped CaF crystals. The spectral analysis reveals the potential mechanism underlying the red-to-green (R/G) ratio transformation; specifically, the cross-relaxation rates of different clusters differed significantly. Based on this result, a strategy of cluster-controlled Er R/G ratio has been proposed and verified by Er and Y co-doped CaF crystals. Our findings provide valuable insights for further design and precise control of Er ion luminescence.
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http://dx.doi.org/10.1364/OE.555976 | DOI Listing |
Sci Rep
September 2025
New Industry Creation Hatchery Center, Tohoku University, Sendai, 980-8579, Japan.
Calcium fluoride crystals doped with europium (CaF[Formula: see text]:Eu) have long been used as conventional inorganic scintillators. Their luminescence is primarily attributed to emission from Eu[Formula: see text] centers, typically around 420 nm. However, it has been reported that increasing the Eu concentration leads to enhanced Eu[Formula: see text] emission in the wavelength range of 590-700 nm.
View Article and Find Full Text PDFSci Rep
August 2025
Department of Basic and Applied Sciences for Engineering, Sapienza University of Rome, 00161, Rome, Italy.
This study explores the potential of Bloch surface waves (BSWs) at the interface of a finite one-dimensional photonic crystal (1D-PC) and vacuum, exploiting spectroscopic ellipsometry in a range that encompasses the mid-infrared (4000 cm to 200 cm). BSWs can be excited in both σ and π polarizations, which in the ellipsometric configuration can be detected at the same time, presenting distinct advantages for sensor applications targeting the growth of thin solid films and molecular monolayers, surface-adsorbed gas molecules, and liquid droplets. Compared to other sensing techniques exploiting mid-infrared vibrational absorption lines for chemical-specific sensitivity, like waveguides, nano-antenna arrays, metasurfaces, attenuated total reflectance (ATR) in crystals or in optical fibers, the present approach features high field enhancements, strong field confinement, and large quality factors of the resonances, all while relying on a rather simple and potentially low-cost configuration.
View Article and Find Full Text PDFThe evolution of Er clusters in CaF crystals has not been fully understood, making the underlying mechanism for regulating the upconversion luminescence color of Er:CaF crystals remains unclear. In this work, the first-principles calculation is combined with the synchrotron X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), as well as the dielectric spectra and absorption spectra to study the Er-doped CaF crystals. The spectral analysis reveals the potential mechanism underlying the red-to-green (R/G) ratio transformation; specifically, the cross-relaxation rates of different clusters differed significantly.
View Article and Find Full Text PDFWe conducted a comprehensive study on the optical spectroscopy properties and laser performances of a Yb, Y: CaF-SrF co-doping mixed crystal. Our investigation included an analysis of the absorption, emission, and gain cross-sections, and we were able to achieve a wide tuning range of 75.4 nm.
View Article and Find Full Text PDFPhys Chem Chem Phys
July 2025
State Key Laboratory of Intelligent Manufacturing Equipment and Technology, School of Mechanical Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074, China.
Calcium fluoride (CaF) crystals are regarded as ideal materials for optical components due to their excellent ultraviolet (UV) transmittance and optical anisotropy. High-precision and low-damage CaF crystals can be prepared by ion beam processing, but the atomic-scale surface and interfacial stability under ion beam processing remains poorly understood. In this paper, a machine learning potential (DP) based on the DeePMD method was developed to explore the underlying physical mechanisms of microstructure and property changes in calcium fluoride under ion beam bombardment.
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