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Polarization Multiplexing Terahertz Metasurfaces through Spatial Femtosecond Lasera??Shaping Fabrication
摘要： Terahertz (THz) metasurface has emerged as a powerful technique to fully modulate the wavefronts of THz radiation. To improve the information storage capability and enhance the encryption security of THz metasurface holograms, smart metasurface designs, and fabrications for polarization multiplexing are essential. In this study, two kinds of polarization multiplexing THz metasurfaces are fabricated through the slit-based spatial modulation of femtosecond laser. Controllable elliptical aperture arrays can easily and flexibly be fabricated on gold films by adjusting the width and position of the slit combined with the laser pulse energy. Based on the Pancharatnam–Berry phase and amplitude modulation, respectively, THz metasurfaces, with two independent target phases or amplitude profiles, are obtained. A variety of information can be processed under different polarization states through these THz metasurfaces. This method allows flexible and efficient customization of THz metasurfaces because of the high-speed fabrication and reproducibility as well as precise control of elliptical apertures location on the surface.
关键词： spatial shaping,THz metasurface,femtosecond laser fabrication,polarization multiplexing
更新于2025-09-23 15:19:57
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Patterned arrays of assembled nanoparticles prepared by interfacial assembly and femtosecond laser fabrication
摘要： Creating shape-defined structures of inorganic nanoparticles in a maskless and template-free fashion would advance the engineering of nanoparticle-based devices and structures with desired configurations for various applications. In this work, a novel fabrication protocol combining bottom-up interfacial assembly and subtractive laser patterning was developed for creating patterned arrays of assembled nanoparticles. A solid film of magnetic nanoparticles (10 nm, monodisperse CoFe2O4) was assembled as a nanoparticle film (thickness less than 100 nm) on liquid interface under guiding field, and it was further transferred to Si substrate followed by selective material removal using femtosecond laser pulses, producing patterned arrays (typical size of 3 μm) of assembled nanoparticles. The size, shape, and arrangement of the patterned arrays were finely regulated by adjusting the laser pulse energy and laser scanning path. The magnetization behavior and magnetic anisotropy of the patterned arrays differ from those of the nanoparticle-assembled film, as reflected by the changes of coercivity and squareness along the out-of-plane direction. The presented fabrication protocol is compatible with microelectronic fabrication techniques and can be applied to various inorganic nanoparticles.
关键词： Magnetic properties,Femtosecond laser fabrication,Interfacial assembly,Nanoparticle patterning,Collective properties
更新于2025-09-19 17:13:59
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Femtosecond laser fabrication of silver nanostructures on glass for surface enhanced Raman spectroscopy
摘要： We report on an optimized fabrication protocol for obtaining silver nanoparticles on fused silica substrates via laser photoreduction of a silver salt solution. We find that multiple scans of the laser over the surface leads to a more uniform coverage of densely packed silver nanoparticles of approximately 50 nm diameter on the fused silica surface. Our substrates yield Raman enhancement factors of the order of 1011 of the signal detected from crystal violet. We use a theoretical model based on scanning electron microscope (SEM) images of our substrates to explain our experimental results. We also demonstrate how our technique can be extended to embedding silver nanoparticles in buried microfluidic channels in glass. The in situ laser inscription of silver nanoparticles on a laser machined, sub-surface, microfluidic channel wall within bulk glass paves the way for developing 3D, monolithic, fused silica surface enhance Raman spectroscopy (SERS) microfluidic sensing devices.
关键词： SERS,surface enhanced Raman spectroscopy,microfluidic sensing devices,femtosecond laser fabrication,silver nanostructures
更新于2025-09-11 14:15:04
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External Field-Controlled Ablation: Magnetic Field
摘要： The femtosecond laser ablation of silicon amidst an externally applied magnetic ?eld in different orientations was investigated with respect to the scanning direction and polarisation of the laser beam, by observation of ablation patterns and debris displacement in a range of ?uences, magnetic ?elds strengths, and geometries. Ultra-short ～ 230 fs laser pulses of 1030 nm wavelengths were utilised in the single and multi-pulse irradiation modes. Ablation with an externally applied magnetic B-?eld Bext ≈ 0.15 T was shown to strongly affect debris formation and deposition. The mechanism of surface plasmon polariton (SPP) wave can explain the ablated periodic patterns observed with alignment along the magnetic ?eld lines. The application potential of external ?eld controlled ablation is discussed.
关键词： magnetic ?eld,ablation,femtosecond laser fabrication
更新于2025-09-11 14:15:04