Direct femtosecond laser surface nano/microstructuring and its applications

Abstract

This paper reviews a new field of direct femtosecond laser surface nano/microstructuring and its applications. Over the past few years, direct femtosecond laser surface processing has distinguished itself from other conventional laser ablation methods and become one of the best ways to create surface structures at nano‐ and micro‐scales on metals and semiconductors due to its flexibility, simplicity, and controllability in creating various types of nano/microstructures that are suitable for a wide range of applications. Significant advancements were made recently in applying this technique to altering optical properties of metals and semiconductors. As a result, highly absorptive metals and semiconductors were created, dubbed as the “black metals” and “black silicon”. Furthermore, various colors other than black have been created through structural coloring on metals. Direct femtosecond laser processing is also capable of producing novel materials with wetting properties ranging from superhydrophilic to superhydrophobic. In the extreme case, superwicking materials were created that can make liquids run vertically uphill against the gravity over an extended surface area. Though impressive scientific achievements have been made so far, direct femtosecond laser processing is still a young research field and many exciting findings are expected to emerge on its horizon.

Femtosecond laser-induced microstructures on Ti substrates for reduced cell adhesion

“…The best results regarding suppression of cell growth were obtained on spike structures which were additionally electrochemically oxidized under acidic conditions. feedback phenomena into characteristic self-ordered surface morphologies, such as nanometric laser-induced periodic surface structures (LIPSS) [10][11][12][13] or micrometer-sized grooves and conical spikes [14,15]. The feedback mechanism during repetitive treatments selects specific spatial periods of the roughness distribution that can absorb radiation better [16].…”

Periodic surface structure creation by UV femtosecond pulses on silicon

“…Ultrashort laser pulses are especially promising for micromachining of various materials, since high energy density can be transferred to the materials in such a short timeframe, that thermal effects on the material are minimal. Femtosecond laser nano-and microstructuring has been investigated for the past decade [5][6][7][8][9]. The formation of laser-induced periodic surface structures (LIPSS) on silicon and on other materials is extensively investigated both theoretically and experimentally [10][11][12][13][14][15][16][17].…”

Nanoscale structures generation within the surface layer of metals with short UV laser pulses

“…The growth of ultrashort pulse laser technologies has opened up new opportunities for high-precision processing of a wide range of materials, including dielectrics, semiconductors, and metals, thus, enabling numerous practical applications in the fields ranging from micromachining to photonics and life sciences [1][2][3]. The ability of ultrashort lasers to deposit energy into a much localized volume of the irradiated target makes it possible to perform very selective material modification and, at the same time, provides unique opportunities for investigating material behavior and properties under extreme conditions of strong electronic excitation, rapid heating and cooling, and ultrafast laser-induced mechanical deformation.…”

“…The ability of ultrashort lasers to deposit energy into a much localized volume of the irradiated target makes it possible to perform very selective material modification and, at the same time, provides unique opportunities for investigating material behavior and properties under extreme conditions of strong electronic excitation, rapid heating and cooling, and ultrafast laser-induced mechanical deformation. This can result in the formation of unique structures in a pre-surface layer of a material affected by the laser deposition [1][2][3].…”