Ultrafast laser synthesis and processing of materials is a burgeoning field that is still in its infancy. This article and the theme articles in this issue review recent developments in the fundamental physics of ultrafast laser–solid interactions as well as the state of our understanding of ultrafast laser-driven surface morphology, modification of transparent media, 3D photo-polymerization and additive fabrication, spallation of graphene, and biological interactions. Also reviewed is the current state of emerging commercial high average power lasers, central to the widespread adoption of ultrafast laser synthesis and processing of materials. It is remarkable that ultrafast lasers with 20 to 600 femtosecond pulse duration can have such a dramatic impact on materials. As we learn more about the fundamental mechanisms that drive the ultrafast laser-material response, even more applications are anticipated to emerge. This revolutionary approach to materials synthesis and processing has already spawned several commercial technologies and promises to create many more in the near future.

Microchips have revolutionized biological analysis since they can be used to perform biochemical analysis with high efficiency and accuracy. Femtosecond laser direct writing followed by wet chemical etching can be used to fabricate hollow microstructures with almost any three-dimensional (3D) structure without stacking or bonding. This permits microfluidic systems to be integrated with micro-optical components (e.g., mirrors and lenses) and micromechanical components (e.g., valves and pumps) in a glass chip by a single continuous process. Furthermore, other micro-optical components such as optical waveguides and attenuators can be integrated by additional femtosecond laser direct writing. Thus, femtosecond laser direct writing can be used to fabricate functional microfluidics, optofluidics, lab-on-a-chip devices, and micro-total analysis systems. In this study, 3D femtosecond laser micromachining is used to fabricate microchips integrated with functional microcomponents for biological analysis. Optofluidic systems, in which microfluidic components are integrated with micro-optical components, are used to detect single cells and perform high-sensitivity analysis of liquid samples by optical methods. Another interesting microchip is introduced, namely nanoaquariums, which is used for performing dynamic observations of microorganisms and bacteria and allows the functions of microorganisms and bacteria to be determined, such as elucidation of the gliding mechanism of Phormidium to seedling roots for growth acceleration of vegetables.

Laser direct-write (LDW) is an established technology for manufacturing electronic and optoelectronic appliances such as cellular telephones, digital cameras, and notebook-type personal computers. One of the most successful applications is laser drilling of via holes on printed circuit boards for the manufacture of cellular telephones. Other practical applications include marking, dicing, trimming, repairing, patterning, bending, and rapid prototyping. In this article, the state of the art of LDW for industrial applications in Japan, the United States, and Europe is reviewed, and its future prospects are discussed.

3D microstructuring of photosensitive glass is demonstrated by femtosecond (fs) laser for lab-on-a-chip manufacture. True 3D hollow microstructures embedded in the glass are fabricated by the fs laser direct write followed by heat treatment and successive wet etching. A variety of microcomponents for a lab-on-a-chip device like a microfluidics, a microvalve, a microoptics, a microlaser, etc. are fabricated by using this technique. The fs laser direct write process is also applied for selective metallization of internal walls of the hollow microstructures embedded in the glass for electric control of movement of the micromechanical components in the lab-on-a-chip device.

The chemical stability of the surface of metals, such as aluminum and stainless steel (SUS304), exposed to acid solutions is remarkably improved by the digital growth of Al2O3 using the sequential surface chemical reaction of trimethylaluminum (TMA) and water vapor. Samples thus coated with Al2O3 thin films were not etched by 1 N HCl or 1 N H2SO4 completely, and no change in the surface morphology was observed by these immersion tests. By the quantitative verification of polarization measurement in 1 N HCl and 1 N H2SO4, the polarization resistance was estimated to be 1.4 × 101–5.18 × 103 times that of noncoated samples. Anticorrosion coating of SUS304 pipe walls was also demonstrated.

The chemical stability of the surface of stainless steel (SUS) 304 in acid immersion tests is greatly improved by the laser implant-deposition (LID) process, i.e., the simultaneous deposition and incorporation of silicon by KrF excimer laser irradiation. The etching depths of the treated samples in 1.32 N HCl solution are substantially zero at the laser irradiation conditions of more than 40 pulses and of more than 400 mJ/cm2 at the surface. By the quantitative verification of cathodic polarization in 1 N H2SO4, the highest polarization resistance is estimated to be 26.7 times that of the nontreated sample.

Surface hardening of SUS304 resulting from the process of doping and deposition of Si by irradiation of a KrF excimer laser beam in a SiH4 gas ambient is investigated, and variations of the surface hardness are examined for different numbers of laser pulses and the laser fluences. The hardening is due to Si incorporation in high concentration. The continuous distribution of Si atoms across the surface layer suggests that a very high adhesion strength of the deposited Si films can be formed. The specific process for surface modification is referred to as laser implant-deposition (LID).