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High-Speed All-Optical Modulator Based on a Polymer Nanofiber Bragg Grating Printed by Femtosecond Laser
摘要： On-chip optical modulator for high-speed information processing system has been widely investigated by majority of researchers but the connection with the fiber system is a difficulty. The fiber-based optical modulator is a good solution to this problem. Fiber Bragg Grating has good potential to be used as an optical modulator because of its linear temperature response, narrow bandwidth, and compact structure. In this paper, a new fiber-integrated all-optical modulator has been realized based on a polymer nanofiber Bragg grating printed by femtosecond laser. This device exhibits a fast temporal response of 176 ns and a good linear modulation of -45.43 pm/mW. Moreover, its stability has also been studied. This work firstly employs Bragg resonance to realize a fiber-integrated all-optical modulator and paves the way toward realization of multifunctional lab-in-fiber devices.
关键词： polymer fiber,all-optical modulator,fiber Bragg grating,femtosecond laser micromachining,multi-photon polymerization
更新于2025-09-12 10:27:22
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A novel methodology for spark gap monitoring in Micro-EDM using optical fiber Bragg grating
摘要： Micro-Electric Discharge Machining (Micro-EDM) are the most considerable micro-manufacturing process used to engineer miniaturized features on any high temperature resistive hard material. The machining parameters in Micro-EDM are very stochastic in nature. The spark gap measure acts as a vital parameter that correlates with other process parameters for enhancement of Material Removal Rate (MRR) in Micro-EDM. Real-time actual measurement of spark gap between the electrodes is highly challenging and is limited due to the small gap measure. The present work is on development of a novel sensing technique for spark gap measurement, based on a Fiber Bragg Grating (FBG) sensor. The sensing system is developed on a cantilever structure bonded with the FBG sensor, for determining accurate spark gap measure with displacement measurement of the tool electrode. The deflection on the cantilever during spark gap generation is translated into strain variations monitored by the FBG bonded over it. Experimental trials are conducted on Micro-EDM set-up with the cantilever beam based displacement sensing with a sensitivity of 10 μm/pm. Real-time spark gap data obtained by FBG are in the range of 1.1-18.6 μm and are validated against a precision measuring instrument. This sensing technology employed for Micro-EDM spark gap measurement establishes a novel technique in micromachining field and formulates a smart system.
关键词： Cantilever beam structure,Micromachining,Spark gap,Fiber optics,Micro-EDM,Bragg Gratings
更新于2025-09-12 10:27:22
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[IEEE 2018 Progress in Electromagnetics Research Symposium (PIERS-Toyama) - Toyama (2018.8.1-2018.8.4)] 2018 Progress in Electromagnetics Research Symposium (PIERS-Toyama) - A Chip of Pulse-Laser-Assisted Dual-Beam Fiber-Optic Trap
摘要： Compared with the single-beam gradient optical trap, the dual-beam optical trap based on micro-structure eliminates the need for complex optical alignment and offers intrinsic benefits of miniaturization and stabilization, which are crucial for developing a practical sensor. We design a monolithic chip of dual-beam fiber-optic trap which allows extremely accurate alignment of submicron scale between two counter-propagating fiber beams. Based on micromachining technology, the chip featured a V-shaped groove to align the fibers and a rectangular channel to load the particles is experimentally realized. Recent studies have demonstrated that micro-scale particles can be removed effectively from substrate by focused pulse laser beam. To acquire high trapping efficiency and better trapping stability, we propose a new loading method that combinates pulse laser with dual-beam fiber-optic trap. We have fabricated a silica miniature operating rod for initial storage of the microspheres and moved a targeted particle into the effective trapping area of the fiber-optic trap. Optical loading and trapping of a 10 μm polystyrene particle in air are demonstrated and the controllable capturing process avoids any contamination on fiber ends, which ensures the reliability of optical path. We use a microscopic imaging system and image processing method to test the static stability of the captured particle. The static stability of the microspheres is submicron, which is clearly superior to the test results in liquid environment. The rapid loading and manipulation of microspheres in optical trap is significant for its applications in optomechanics and precision force sensing. Our results pave the way for a new class of monolithic and portable optical sensor for inertial measurement.
关键词： micromachining,fiber-optic trap,optical sensor,dual-beam optical trap,pulse laser
更新于2025-09-12 10:27:22
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Nanosecond laser ablation of the trapezoidal structures for turbomachinery applications
摘要： Correctly designed nature inspired micrometer size grooves i.e. riblets can be used to reduce drag. There exist several methods to manufacture these structures but all of them have their own problems and disadvantages, wherefore they are not perfectly suitable for all real industrial applications. Aim of this paper is to show how a short nanosecond pulse laser ablation can be applied in a micrometer size trapezoidal shape structures i.e. riblets manufacturing for a turbomachinery applications. It is shown that although the quality of the riblets, fabricated with this method, is not as good as with the best possible manufacturing methods, it is still enhancing the properties. Added to this, the processing speed is fast enough and acquisition costs of the system are economic so that method is suitable for the real industrial application. The wind tunnel studies indicate that the fabricated riblets on an airfoil reduce wall shear stress compared to a smooth airfoil without structuring.
关键词： micromachining,nanosecond laser,airfoil,riblet,microstructures,Laser ablation
更新于2025-09-12 10:27:22
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Fabrication of surfaces with reduced friction using nanosecond laser
摘要： In this paper a short i.e. nanosecond pulse laser ablation is utilized to fabricate trapezoidal shaped microstructures i.e. riblets that are known to reduce friction. They can be applied for example in turbomachinery applications to make system more economical by reducing the wall shear stress on flow surfaces. Previously, these structures have been manufactured using different methods like grinding and ultrashort pulse lasers. The methods used before have their disadvantages and therefore they cannot be utilized in all applications. By using the nanosecond pulse laser instead of the shorter pulses, it is possible to manufacture riblets with a high fabrication speed and economically. Although a quality of the nanosecond pulse laser manufactured riblets is not as good as ones fabricated with the ultrashort pulse lasers, they are still able to reduce friction in the turbomachinery application.
关键词： micromachining,tubomachinery,nanosecond laser,airfoil,riblet,laser ablation,microstructures
更新于2025-09-12 10:27:22
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Femtosecond-laser-written optofluidics in alumino-borosilicate glass
摘要： Femtosecond Laser Irradiation followed by Chemical Etching (FLICE) is a powerful technique for prototyping three-dimensional microfluidic structures in glass. Direct inscription of optical waveguides, by the same femtosecond laser, enables rapid fabrication of optofluidic devices for chemistry or biology applications. As a matter of fact, substrates where FLICE is known as most effective, such as fused silica, are not optimal for laser inscription of high-contrast optical waveguides, thus limiting the potentials of this technology. Here we show that it is possible to apply FLICE also to a commercial alumino-borosilicate glass, where very complex and low-loss photonic circuitry has been demonstrated recently. Besides optimizing the irradiation parameters to achieve hollow structures with high aspect-ratio, we investigate the etching dynamics and the micro-morphology of the etched regions. As a test for the technique, we realize an optofluidic device composed of a microchannel and two intersecting optical waveguides.
关键词： Borosilicate glass,Microfluidics,Femtosecond laser micromachining
更新于2025-09-12 10:27:22
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Femtosecond Laser Micromachining of Metal Thin Films
摘要： In this paper the possibilities of femtosecond laser micromachining of thin-film titanium coatings for elements of microelectronics and optoelectronics are considered. Using pulsed laser deposition in vacuum (wavelength λ = 1030 nm, pulse repetition frequency f = 10 kHz, Emax pulse energy ≈ 150 μJ, pulse duration τ ≈ 280 fs), a thin-film titanium coating was obtained on the surface of the quartz substrate. An example of the formation of an element of a given geometry by selective laser ablation of areas of a deposited metal coating is shown.
关键词： ultrashort laser pulses,precision micromachining,laser ablation,thin metal films
更新于2025-09-12 10:27:22
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Maskless, rapid manufacturing of glass microfluidic devices using a picosecond pulsed laser
摘要： Conventional manufacturing of glass microfluidic devices is a complex, multi-step process that involves a combination of different fabrication techniques, typically photolithography, chemical/dry etching and thermal/anodic bonding. As a result, the process is time-consuming and expensive, in particular when developing microfluidic prototypes or even manufacturing them in low quantity. This report describes a fabrication technique in which a picosecond pulsed laser system is the only tool required to manufacture a microfluidic device from transparent glass substrates. The laser system is used for the generation of microfluidic patterns directly on glass, the drilling of inlet/outlet ports in glass covers, and the bonding of two glass plates together in order to enclose the laser-generated patterns from the top. This method enables the manufacturing of a fully-functional microfluidic device in a few hours, without using any projection masks, dangerous chemicals, and additional expensive tools, e.g., a mask writer or bonding machine. The method allows the fabrication of various types of microfluidic devices, e.g., Hele-Shaw cells and microfluidics comprising complex patterns resembling up-scaled cross-sections of realistic rock samples, suitable for the investigation of CO2 storage, water remediation and hydrocarbon recovery processes. The method also provides a route for embedding small 3D objects inside these devices.
关键词： glass microfluidic devices,laser micromachining,picosecond pulsed laser,maskless manufacturing,laser microwelding,rapid prototyping
更新于2025-09-12 10:27:22
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Experimental study of droplet shedding on laser-patterned substrates
摘要： An experimental study was performed to investigate the dynamics of droplet shedding under the effect of various shear flow speeds on a laser micromachined surface with superhydrophobic properties. To account for the effect of liquid properties on droplet shedding, four different liquids were used in these sets of experiments, namely, distilled water, ethylene glycol, propylene glycol, and glycerol. The wetting length of the liquid droplets was measured based on the air shear speed, and three different regimes were observed based on the critical Weber and Ohnesorge numbers. In the first regime, where the Weber and Ohnesorge numbers are low, droplets deform with slight movement or rotation without detachment from the surface. Under the second regime, where the Weber number is relatively high and the Ohnesorge number is low, droplets deform and detach from the surface, and then subsequent breakup may occur. The variation of droplet detachment time with the Weber and Ohnesorge numbers is further discussed in this paper. In the third regime, where the Ohnesorge number is high, there is no droplet detachment nor are rivulets formed. Finally, empirical correlations are developed to predict the droplet behavior on laser-patterned surfaces under the effect of shear flow. This work can be used as a baseline to study the droplet dynamics on a superhydrophobic surface in cases where temperature changes the liquid properties.
关键词： superhydrophobic surfaces,Ohnesorge number,droplet shedding,laser micromachining,Weber number
更新于2025-09-12 10:27:22
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Faster Femtosecond Laser Processing using a Dual-Focus SLM Emulated Lens
摘要： The generation of multiple beams is an established method to increase the processing speed of advanced laser-based material processing techniques. This multi-foci approach has shown promising results in laser micromachining, scanning microscopy, optical data storage, or optical tweezer arrays. Of particular interest is its application to manufacturing bigger objects where laser treatment is required over surfaces on the centimetre scale or larger. Using a Spatial Light Modulator (SLM), such parallelisation has been studied over the last few years by splitting the input beam into multiple beams (up to 1000 beams [1]) for simultaneous machining on a plane perpendicular to the propagation axis. This method is primarily based on holographic femtosecond laser processing [2] where computer-generated holograms (CGH) are displayed on an SLM. Further applications include phase distortion and lens aberration correction [3], or for four-dimension light shaping [4]. The SLM provides unique features for dynamic pulse shaping, more efficient use of the laser energy, or the machining of complex shapes.
关键词： spatial light modulator,laser micromachining,computer-generated holograms,dual-focus SLM,femtosecond laser processing
更新于2025-09-12 10:27:22