Laser Fabrication of Nanoholes on Silica through Surface Window Assisted Nano-Drilling (SWAN)

Rapid Fabrication of Wavelength-Scale Micropores on Metal by Femtosecond MHz Burst Bessel Beam Ablation

The preparation of the wavelength-scale micropores on metallic surfaces is limited by the high opacity of metal. At present, most micropores reported in the literature are more than 20 µm in diameter, which is not only large in size, but renders them inefficient for processing so that it is difficult to meet the needs of some special fields, such as aerospace, biotechnology, and so on. In this paper, the rapid laser fabrications of the wavelength-scale micropores on various metallic surfaces are achieved through femtosecond MHz burst Bessel beam ablation. Taking advantage of the long-depth focal field of the Bessel beam, high-density micropores with a diameter of 1.3 µm and a depth of 10.5 µm are prepared on metal by MHz burst accumulation; in addition, the rapid fabrication of 2000 micropores can be achieved in 1 s. The guidelines and experimental results illustrate that the formations of the wavelength-scale porous structures are the result of the co-action of the laser-induced periodic surface structure (LIPSS) effect and Bessel beam interference. Porous metal can be used to store lubricant and form a lubricating layer on the metallic surface, thus endowing the metal resistance to various liquids' adhesion. The microporous formation process on metal provides a new physical insight for the rapid preparation of wavelength-scale metallic micropores, and promotes the application of porous metal in the fields of catalysis, gas adsorption, structural templates, and bio-transportation fields.

Insight on the regulation mechanism of the nanochannels in hard and brittle materials induced by sparially shaped femtosecond laser

The efficient fabrication of nanochannels on hard and brittle materials is a difficult task in the field of micro and nano processing. We have realized nanochannel arrays on silica with characteristic scales varying from 50–230 nm using a single femtosecond Bessel beam pulse of 515 nm. By characterizing the surface openings, we found that the characteristic scales of the nanopore openings are inextricably linked to the surface energy deposition effect. We achieved not only three asymmetric channel profiles by adjusting the laser-sample interaction region, but also high aspect ratio nanochannels with characteristic scales about 50 nm and aspect ratios over 100. These results on hard and brittle materials provide a broader platform and application scenarios for smart particle rectifiers, DNA molecular sequencing, biosensors, and nanofluidic devices, which are also more suitable for future practical applications due to their low cost, good durability, and high productivity.

High-quality rapid laser drilling of transparent hard materials

In this study, a hybrid method for high-quality rapid drilling of transparent hard materials which combines femtosecond laser (fs-laser) Bessel beam modifying materials and selective wet etching is presented. Using this method, micro-holes with no taper of different sizes (from 10 to 35 μm) and shapes (square, triangle, circular, and pentagram) are fabricated. Bessel beams of different lengths can be generated flexibly by loading different computer-generated holograms (CGHs) into the spatial light modulator (SLM) and the maximum length of light interacting with materials can reach 320 μm, leading to a reduction of the laser scanning time by two orders of magnitude. Moreover, a set of three-dimensional multi-layer submicron through-holes in crystal materials is also realized, with an aspect ratio of more than 1000 for each hole. These results indicate that this method has broad application potential in chip packaging, aviation manufacturing, single particle catalysis, and other fields.