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We propose, analyze and optimize a two-dimensional conical photonic crystal geometry to enhance light extraction from a high refractive index material, such as an inorganic scintillator. The conical geometry suppresses Fresnel reflections at an optical interface due to adiabatic impedance matching from a gradient index effect. The periodic array of cone structures with a pitch larger than the wavelength of light diffracts light into higher-order modes with different propagating angles, enabling certain photons to overcome total internal reflection (TIR). The numerical simulation shows simultaneous light yield gains relative to a flat surface both below and above the critical angle and how key parameters affect the light extraction efficiency. Our optimized design provides a 46% gain in light yield when the conical photonic crystals are coated on an LSO (cerium-doped lutetium oxyorthosilicate) scintillator.
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http://dx.doi.org/10.1364/OE.23.022730 | DOI Listing |
Chem Sci
August 2025
State Key Laboratory of Chemical Reaction Dynamics and Dalian Coherent Light Source, Dalian Institute of Chemical Physics, Chinese Academy of Sciences 457 Zhongshan Road Dalian 116023 China
We report time-sliced velocity map imaging studies of the methyl (CH) and electronically excited sulfur (S(D)) fragments formed following the photoexcitation of jet-cooled CHSH molecules in the 2A'' ← X̃ A' absorption band (. at wavelengths in the range 190 ≤ ≤ 210 nm). Analyses of images of CH fragments in their = 0, 1 and 2 vibrational levels confirm the perpendicular parent transition dipole moment and prompt bond fission and show that the ground state SH(X) partners are formed with an inverted vibrational population distribution, peaking at = 2 at the shortest excitation wavelengths investigated.
View Article and Find Full Text PDFThis study introduces a hybrid, integrated two-dimensional multi-layer optical phased array architecture that is characterized by its compactness, low loss, high performance, and versatility. It is suitable for applications ranging from space communication to sensor integration. We have delineated the essential requirements for cost-effective, miniaturized, and widely applicable heterostructure silicon photonics and highlighted the benefits of this architectural approach.
View Article and Find Full Text PDFACS Nano
July 2025
Department of Physics, Cavendish Laboratory, University of Cambridge; Cambridge CB3 0HE, U.K.
Defect engineering in transition metal dichalcogenide (TMD) monolayers enables applications in single-photon emission, sensing, and photocatalysis. These functionalities critically depend on defect type, density, spatial distribution, relative energy, and the dynamics of exciton trapping at the defect sites. The latter are mediated by coupling to optical phonons through mechanisms not yet fully understood.
View Article and Find Full Text PDFLuminescence
July 2025
Department of Chemistry, University of North Bengal, Darjeeling, West Bengal, India.
Nerve agents seriously threaten the viability of the contemporary environment and public health. In the current contribution, we have introduced a Schiff base-based probe, MIDA to "detect and degrade" sarin simulant, diethyl chlorophosphate (DCP) in solution and gaseous phases. MIDA is highly selective and sensitive towards DCP emitting a highly intensified yellow fluorescence having detection and quantification limits within the μM range.
View Article and Find Full Text PDFJ Chem Phys
July 2025
Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
Conical intersections (CIs), or diabolic points, play a critical role in fast electronic energy relaxation in aromatic molecules and their aggregates. While it is recognized that vibronic coupling drives the dynamics through CIs, there is a paucity of experimental information on the effect of vibrations on relaxation in molecular aggregates. Here, we describe experiments on the ultrafast electronic energy relaxation in the isolated anthracene dimer-an archetype of a π-stacked aromatic system relevant to intermolecular photon-driven processes such as those in optoelectronics.
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