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[Laser Institute of America ICALEO? 2016: 35th International Congress on Applications of Lasers & Electro-Optics - San Diego, California, USA (October 16–20, 2016)] International Congress on Applications of Lasers & Electro-Optics - Self-accelerating bessel-like vortex beams: A new tool for optical manipulation
摘要： Over the past decade, the field of optical manipulation has been “shaped” by intelligent design of nonconventional optical beams. In particular, optical beams carrying angular momentum have provided a new twist to optical tweezers, enabling dynamical spin and rotation of trapped particles. Although optical vortex beams, nondiffracting Bessel beams, and recently, self-accelerating Airy beams have each played a unique role in the arena of particle trapping and manipulation, combining their features would certainly lead to a more powerful tool. A few years ago, we designed and demonstrated diffraction-resisting Bessel-like beams that travel along arbitrary trajectories. With the similar method, the singular beam was shaped in this paper, which owns the form of a higher-order Bessel function with a preserving OAM and a nonexpanding dark “hole” in the main lobe of the beam. The beam can propagate along an arbitrary trajectory, including parabolic, hyperbolic and even three-dimensional trajectories. Experimentally, not only we observe such a curved singular beam, but also we employ it to optically trap and rotate microparticles in a 3D spiral motion under the combined action of radiation pressure, gradient force, and the OAM. Our findings may open up new avenues for shaped light in various applications.
关键词： Self-accelerating,particle manipulation,Nondiffracting beams,Bessel-like Vortex beams
更新于2025-09-16 10:30:52
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In-fibre particle manipulation and device assembly via laser induced thermocapillary convection
摘要： The ability to manipulate in-fibre particles is of technological and scientific significance, yet particle manipulation inside solid environment remains fundamentally challenging. Here we show an accurately controlled, non-contact, size- and material-independent method for manipulating in-fibre particles based on laser-induced thermocapillary convection. The laser liquefaction process transforms the fibre from a solid media into an ideal fluid environment and triggers the in-fibre thermocapillary convection. In-fibre particles, with diameter from submicron to hundreds of microns, can be migrated toward the designated position. The number of particles being migrated, the particle migration velocity and direction can be precisely controlled. As a proof-of-concept, the laser-induced flow currents lead to the migration-to-contact of dislocated in-fibre p- and n-type semiconductor particles and the forming of dual-particle p-n homo- and heterojunction directly in a fibre. This approach not only enables in-fibre device assembly to achieve multi-component fibre devices, but also provide fundamental insight for in-solid particle manipulation.
关键词： in-fibre particle manipulation,p-n junction,laser-induced thermocapillary convection,multi-component fibre devices
更新于2025-09-16 10:30:52
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Fabrication of Silicon Microfluidic Chips for Acoustic Particle Focusing Using Direct Laser Writing
摘要： We have developed a fast and simple method for fabricating microfluidic channels in silicon using direct laser writing. The laser microfabrication process was optimised to generate microfluidic channels with vertical walls suitable for acoustic particle focusing by bulk acoustic waves. The width of the acoustic resonance channel was designed to be 380 μm, branching into a trifurcation with 127 μm wide side outlet channels. The optimised settings used to make the microfluidic channels were 50% laser radiation power, 10 kHz pulse frequency and 35 passes. With these settings, six chips could be ablated in 5 h. The microfluidic channels were sealed with a glass wafer using adhesive bonding, diced into individual chips, and a piezoelectric transducer was glued to each chip. With acoustic actuation at 2.03 MHz a half wavelength resonance mode was generated in the microfluidic channel, and polystyrene microparticles (10 μm diameter) were focused along the centre‐line of the channel. The presented fabrication process is especially interesting for research purposes as it opens up for rapid prototyping of silicon‐glass microfluidic chips for acoustofluidic applications.
关键词： acoustophoresis,acoustofluidics,ultrasound,laser micromachining,particle manipulation,microfabrication
更新于2025-09-16 10:30:52