Advanced Photonics Research最新文献

Recently, the transparent metasurface has widely attracted attention for its excellent performance and potential application in next generation of glass curtain walls and aircraft canopies. Yet, the existing metasurfaces suffer from the drawback of designer experience. Here, we propose a momentous scheme to design transparent metasurface using an accelerated elitist-preserving genetic algorithm based on a geometric coding method. To verify the scheme, a transparently stacked metasurface (TSMS) has been designed for asymmetrical polarization decomposition. Simulated results show that TSMS reflects y-polarized waves into left-handed circularly polarized (LHCP) waves and transmits them into right-handed circularly polarized (RHCP) waves in the band of 8.5–9.7 GHz. The orthogonal circularly polarized waves are realized by TSMS with incidences along opposite direction. Moreover, TSMS reflects or transmits any polarized incidences into LHCP waves in one space and RHCP waves in the other space from 7.57 to 9.72 GHz. As a proof-of-concept, a prototype of TSMS was fabricated and measured in a microwave anechoic chamber. Experimental results coincide well with the simulated data, which demonstrate the characteristics of transparency, asymmetrically bidirectional polarization decomposition, and space selection of circular polarization for TSMS.

A novel aberration-free X-ray compound refractive kinoform lens design based on the Cartesian oval curve is presented, designated as the OVAL-OK (OVAL Overlap Kinoform) lens. Material infilling of the kinoform step structure maintains focal spot dimensions while reducing focal intensity and reproducibility of structures. A SU-8 OVAL-OK lens fabricated through X-ray lithography achieved vertical focal sizes of 70.8 nm (knife-edge scanning) and 56 nm (wavefront propagation analysis) under 15 keV X-ray illumination, using a 120 μm × 200 μm (horizontal × vertical) aperture and 40.8 mm working distance. The lens exhibits a horizontal structural depth of 170 μm and a minimum feature size of 5 μm. The observed discrepancy between direct knife-edge measurements and wavefront-derived values is attributable to the combined effects of geometric, diffraction, coherence, instrumental instability, etc. These results demonstrate the potential for achieving sub-50 nm 2D focusing in future iterations through enhanced structural depth and expanded aperture dimensions.

Laser surface texturing can improve the functional properties of metallic materials, with the texture shape being a crucial factor. The spatial light modulator (SLM) is used to design the shape of individual textures. However, generating deep microtextures with precise shapes on metallic materials currently requires extended processing times, limiting their use in industrial applications. This study investigates the generation of the microtexturing patterns with various shapes on stainless steel 316 L surface using a SLM. The method combining computer-generated holograms with images demonstrates high energy fluence efficiency. The holograms determine the reconstruction distance, shape, and size of the textures. Patterns of the textures with various complex shapes (e.g., circular, triangle, square, hexagon, and other), 6–12 μm depth and 50–70 μm width are achieved using only 5 pulses (200 μs per texture) and 25 kHz pulse frequency rate. This method achieves texturing of 10 × 10 mm areas with various shapes in just 2 s, offering a processing speed ≈500 times faster than current state-of-the-art ultrashort laser pulse techniques, significantly advancing the efficiency of microtexturing processes.

Astrocytes are glial cells with intracellular calcium dynamics essential for brain homeostasis, synaptic modulation, and cognition and altered in neuropathology and neuroinflammation. Growing evidence indicates these calcium signals can be triggered by chemophysical stimuli. Photonic, label free optical stimulation could provide unique opportunities to study astrocytic calcium signaling in physiological and pathological conditions and responses to external cues. This study describes the effects of visible LED light technology, called 40 Hz invisible spectral flicker (ISF), on calcium dynamics in primary rat cortical astrocytes. We demonstrate that ISF and continuous visible light (CL, used as control) can efficiently trigger calcium dynamics in astrocyte, through recruiting distinct molecular pathways. Specifically, extracellular calcium influx is essential for the response to 40 Hz ISF stimulation to occur but not to CL. In addition,the channels TRPV4 and TRPA1, as well as IP₃Rs and ryanodine receptors pathways, are differentially implicated in the observed effects in response to ISF and CL. These findings respond to the need for novel methods to trigger calcium signaling in astrocytes, showing that ISF visible, nonlaser light is an effective approach with potential modulation capability simply varying light stimulation frequency.

Astrocytes are glial cells with intracellular calcium dynamics essential for brain homeostasis, synaptic modulation, and cognition and altered in neuropathology and neuroinflammation. Growing evidence indicates these calcium signals can be triggered by chemophysical stimuli. Photonic, label free optical stimulation could provide unique opportunities to study astrocytic calcium signaling in physiological and pathological conditions and responses to external cues. This study describes the effects of visible LED light technology, called 40 Hz invisible spectral flicker (ISF), on calcium dynamics in primary rat cortical astrocytes. We demonstrate that ISF and continuous visible light (CL, used as control) can efficiently trigger calcium dynamics in astrocyte, through recruiting distinct molecular pathways. Specifically, extracellular calcium influx is essential for the response to 40 Hz ISF stimulation to occur but not to CL. In addition,the channels TRPV4 and TRPA1, as well as IP₃Rs and ryanodine receptors pathways, are differentially implicated in the observed effects in response to ISF and CL. These findings respond to the need for novel methods to trigger calcium signaling in astrocytes, showing that ISF visible, nonlaser light is an effective approach with potential modulation capability simply varying light stimulation frequency.

Laser surface texturing can improve the functional properties of metallic materials, with the texture shape being a crucial factor. The spatial light modulator (SLM) is used to design the shape of individual textures. However, generating deep microtextures with precise shapes on metallic materials currently requires extended processing times, limiting their use in industrial applications. This study investigates the generation of the microtexturing patterns with various shapes on stainless steel 316 L surface using a SLM. The method combining computer-generated holograms with images demonstrates high energy fluence efficiency. The holograms determine the reconstruction distance, shape, and size of the textures. Patterns of the textures with various complex shapes (e.g., circular, triangle, square, hexagon, and other), 6–12 μm depth and 50–70 μm width are achieved using only 5 pulses (200 μs per texture) and 25 kHz pulse frequency rate. This method achieves texturing of 10 × 10 mm areas with various shapes in just 2 s, offering a processing speed ≈500 times faster than current state-of-the-art ultrashort laser pulse techniques, significantly advancing the efficiency of microtexturing processes.

Laser surface texturing can improve the functional properties of metallic materials, with the texture shape being a crucial factor. The spatial light modulator (SLM) is used to design the shape of individual textures. However, generating deep microtextures with precise shapes on metallic materials currently requires extended processing times, limiting their use in industrial applications. This study investigates the generation of the microtexturing patterns with various shapes on stainless steel 316 L surface using a SLM. The method combining computer-generated holograms with images demonstrates high energy fluence efficiency. The holograms determine the reconstruction distance, shape, and size of the textures. Patterns of the textures with various complex shapes (e.g., circular, triangle, square, hexagon, and other), 6–12 μm depth and 50–70 μm width are achieved using only 5 pulses (200 μs per texture) and 25 kHz pulse frequency rate. This method achieves texturing of 10 × 10 mm areas with various shapes in just 2 s, offering a processing speed ≈500 times faster than current state-of-the-art ultrashort laser pulse techniques, significantly advancing the efficiency of microtexturing processes.

Astrocytes are glial cells with intracellular calcium dynamics essential for brain homeostasis, synaptic modulation, and cognition and altered in neuropathology and neuroinflammation. Growing evidence indicates these calcium signals can be triggered by chemophysical stimuli. Photonic, label free optical stimulation could provide unique opportunities to study astrocytic calcium signaling in physiological and pathological conditions and responses to external cues. This study describes the effects of visible LED light technology, called 40 Hz invisible spectral flicker (ISF), on calcium dynamics in primary rat cortical astrocytes. We demonstrate that ISF and continuous visible light (CL, used as control) can efficiently trigger calcium dynamics in astrocyte, through recruiting distinct molecular pathways. Specifically, extracellular calcium influx is essential for the response to 40 Hz ISF stimulation to occur but not to CL. In addition,the channels TRPV4 and TRPA1, as well as IP₃Rs and ryanodine receptors pathways, are differentially implicated in the observed effects in response to ISF and CL. These findings respond to the need for novel methods to trigger calcium signaling in astrocytes, showing that ISF visible, nonlaser light is an effective approach with potential modulation capability simply varying light stimulation frequency.

Optical coherence tomography angiography (OCTA) has become an indispensable tool for visualizing and quantifying in vivo blood flow due to its motion-contrast-based label-free flow detection capabilities. However, in various applications, its effectiveness is hindered by signal degradation due to scattering, absorption, and depth-dependent defocus, which limit penetration into deeper tissues. Depth-dependent defocus is particularly problematic because it not only reduces the visual clarity of blood vessels but also weakens the angiographic decorrelation signal by diminishing both the signal amplitude and the sensitivity to slow flow. This paper presents a novel set of scanning and image processing techniques to computationally mitigate defocus-induced effects in OCT angiograms. Allowing focal plane placement into deeper tissue without degrading the image quality near the surface, the proposed method enables defocus-free, tail-artifact-free, and penetration-enhanced angiography. The approach is compatible with all phase-stable OCTA systems across a wide range of A-scan rates, from sub-MHz to multi-MHz, offering a robust platform for improved angiographic imaging.

Four-Wave Mixing

Four-wave mixing is an enabling technique for optical frequency generation and translation. Boosting four-wave mixing conversion efficiency is of central importance to a variety of applications that require rich spectral information. In their Research Article (10.1002/adpr.70166), Yi Li, Xingchen Ji, Qiancheng Zhao, and co-workers propose a new perspective that field enhancement can be interpreted as an elongation of effective length. A unified framework is established to bridge nonresonant waveguides and resonant cavities and is experimentally verified in the gallium phosphide-on-insulator platform.