Previously, the effect of pulse bandwidth compression or broadening was observed in reflection from a moving front together with the Doppler shift. In this letter, an approach is presented, which alters pulse bandwidth without change in the central frequency. It occurs when light is reflected from a moving front of an otherwise stationary photonic crystal. This means that the photonic crystal lattice as such is stationary and only its boundary to the environment is moving, thus extruding (or shortening) the photonic crystal medium. The compression (broadening) factor depends on the front velocity and is the same as for the conventional Doppler shift. Complete reflection and transformation of the pulse can be achieved even with weak refractive index contrast, what makes the approach experimentally viable.
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http://dx.doi.org/10.1364/OE.22.013280 | DOI Listing |
Biomed Phys Eng Express
January 2025
Physics Department, University at Albany, 1400 Washington Ave, Albany, New York, 12222-0100, UNITED STATES.
Conventional x-ray radiography relies on attenuation differences in the object, which often results in poor contrast in soft tissues. X-ray phase imaging has the potential to produce higher contrast but can be difficult to utilize. Instead of grating-based techniques, analyzer-based imaging, also known as diffraction enhanced imaging (DEI), uses a monochromator crystal with an analyzer crystal after the object.
View Article and Find Full Text PDFSmall
January 2025
Department of Applied Chemistry, National Yang Ming Chiao Tung University, Hsinchu, 300093, Taiwan.
Anticounterfeiting technologies have become increasingly crucial due to the growing issue of counterfeit goods, particularly in high-value industries. Traditional methods such as barcodes and holograms are prone to replication, prompting the need for advanced, cost-effective, and efficient solutions. In this work, a practical application of anodic aluminum oxide (AAO) membranes are presented for anticounterfeiting, which addresses the challenges of high production costs and complex fabrication processes.
View Article and Find Full Text PDFAdv Mater
January 2025
Institute of Materials Physics, University of Münster, Wilhelm-Klemm-Str. 10, 48149, Münster, Germany.
As a phase change material (PCM), antimony exhibits a set of desirable properties that make it an interesting candidate for photonic memory applications. These include a large optical contrast between crystalline and amorphous solid states over a wide wavelength range. Switching between the states is possible on nanosecond timescales by applying short heating pulses.
View Article and Find Full Text PDFNat Mater
January 2025
State Key Laboratory of Surface Physics, Key Laboratory of Micro and Nano Photonic Structures (MOE), and Department of Physics, Fudan University, Shanghai, China.
Polymorphism, commonly denoting diverse molecular or crystal structures, is crucial in the natural sciences. In van der Waals antiferromagnets, a new type of magnetic polymorphism arises, presenting multiple layer-selective magnetic structures with identical total magnetization. However, resolving and manipulating such magnetic polymorphs remain challenging.
View Article and Find Full Text PDFMater Horiz
January 2025
Beijing Key Laboratory for Optical Materials and Photonic Devices, Department of Chemistry, Beijing Advanced Innovation Center for Imaging Theory and Technology, Capital Normal University, Beijing 100048, P. R. China.
Linearly-polarized organic electroluminescent devices have gained significant attention due to their potential applications across various fields. However, traditional thin-film organic light-emitting diodes (OLEDs) face significant challenges, primarily due to the necessity of incorporating complex optical elements. In this study, we present linearly-polarized OLEDs (LP-OLEDs) based on organic single crystals that we have designed and prepared.
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