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Photonic crystal resonators (PhCRs) have been widely used in nonlinear integrated photonics for frequency engineering applications. A microwave-assisted frequency converter based on PhCRs provides precisely controlled bidirectional frequency conversion. Using a hybrid silicon nitride-on-lithium niobate-on-insulator platform, we demonstrate a high-quality PhCR for the first time, to the best of our knowledge, for voltage-driven flexible frequency conversion using the electro-optic effect (0.85 pm/V) without etching lithium niobate. The fabricated PhCR has a large supermode splitting bandwidth of 14.6 GHz and an intrinsic quality factor of 1.47 × 10. Using different periodic corrugation amplitudes in the fabricated PhCRs enables the precise control of mode-splitting bandwidth with a 93.5-MHz/nm bandwidth-to-amplitude ratio.
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http://dx.doi.org/10.1364/OL.565076 | DOI Listing |
Nat Nanotechnol
September 2025
Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA, USA.
Topological photonics explores photonic systems that exhibit robustness against defects and disorder, enabled by protection from underlying topological phases. These phases are typically realized in linear optical systems and characterized by their intrinsic photonic band structures. Here we experimentally study Floquet Chern insulators in periodically driven nonlinear photonic crystals, where the topological phase is controlled by the polarization and the frequency of the driving field.
View Article and Find Full Text PDFCarbohydr Polym
November 2025
Molecular Imaging and Photonics, Department of Chemistry, KU Leuven, Campus Kulak Kortrijk, Etienne Sabbelaan 53, 8500 Kortrijk, Belgium. Electronic address:
Cellulose nanocrystals (CNCs) have emerged as promising candidates for chiroptical functional materials due to their ability to form cholesteric liquid crystals with tunable periodicity. The quality of the final cholesteric phase is influenced by the nucleation, growth and coalescence mechanism of the initial droplets, known as tactoids. Current research focuses on understanding the size and morphological transformations of these tactoids, to gain deeper insights into their dynamic behavior and, in turn, to better control the final properties of novel photonic materials.
View Article and Find Full Text PDFNpj Nanophoton
September 2025
Chair in Hybrid Nanosystems, Nanoinstitute Munich, Faculty of Physics, Ludwig-Maximilians-Universität München, Munich, Germany.
Second-order nonlinear optical processes are fundamental to photonics, spectroscopy, and information technologies, with material platforms playing a pivotal role in advancing these applications. Here, we demonstrate the exceptional nonlinear optical properties of the van der Waals crystal 3R-MoS, a rhombohedral polymorph exhibiting high second-order optical susceptibility ( ) and remarkable second-harmonic generation (SHG) capabilities. By designing high quality factor resonances in 3R-MoS metasurfaces supporting quasi-bound states in the continuum (qBIC), we first demonstrate SHG efficiency enhancement exceeding 10.
View Article and Find Full Text PDFNat Mater
September 2025
Department of Physics, University of Colorado, Boulder, CO, USA.
Time crystals are unexpected states of matter that spontaneously break time-translation symmetry either in a discrete or continuous manner. However, spatially mesoscale space-time crystals that break both space and time symmetries have not been reported. Here we report a continuous space-time crystal in a nematic liquid crystal driven by ambient-power, constant-intensity unstructured light.
View Article and Find Full Text PDFAdv Mater
September 2025
Strait Institute of Flexible Electronics (SIFE, Future Technologies), Fujian Key Laboratory of Flexible Electronics, Fujian Normal University and Strait Laboratory of Flexible Electronics (SLoFE), Fuzhou, 350117, China.
Halide perovskite nanomaterials have emerged as a transformative platform for generating and manipulating polarized luminescence, offering unprecedented opportunities for next-generation optoelectronic technologies. This review comprehensively examines recent advances in engineering both linearly polarized luminescence (LPL) and circularly polarized luminescence (CPL) from perovskite nanostructures, focusing on structural design principles, chirality transfer mechanisms, and performance optimization strategies. Methods are systematically analyzed to achieve polarized emission, including anisotropic nanocrystal growth, chiral ligand functionalization, and liquid crystal-mediated alignment, while highlighting critical optical factors such as dissymmetry factors and photoluminescence quantum yield.
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