The use of ultrashort pulsed lasers in materials processing is an emerging technology. These lasers have the capability to ablate materials precisely with little or no collateral damage, even with materials that are impervious to laser energy from conventional pulsed lasers. The extreme intensities and short timescale at which ultrashort pulsed lasers operate differentiate them from other lasers. The means of ultrashort pulsed laser generation is discussed; included are a survey of pulse compressor techniques with solid state lasers and a brief discussion of excimer-dye lasers. This is followed by a discussion of specific examples of ultrashort pulsed machining of specific materials, along with mechanistic details. Optical breakdown mechanisms, including electron avalanche ionization and multiphoton absorption are discussed. It is shown that as pulse width increases and intensity decreases, laser damage becomes a stochastic process in which the ultrashort pulsed, high intensity light causes optical breakdown over a very narrow range. This, along with the lack of significant thermal conduction, greatly improves the precision of ultrashort pulsed lasers in micromachining applications.

Three-dimensional (3D), periodic nanowriting on diamond clusters is reported in this letter. Concentric circular rings were observed on diamond microclusters, nucleated near the periphery of a laser-irradiated region, when chemical-vapor deposited diamond was processed in air, with laser pulses of 380 fs duration and at a wavelength of 248 nm. Periodic ripples also have been observed on single-crystal and polycrystalline diamond surfaces. Further, it is experimentally shown that the periodicity of these corrugated two-dimensional and 3D structures is shorter than that of the laser wavelength used (248 nm for the excimer fs laser and 825 nm for the Ti–sapphire fs laser).

We report an atomistic simulation study of laser-induced graphitization on the diamond (111) surface. Our simulation results show that the diamond to graphite transition occurs along different pathways depending on the length of the laser pulse being used. Under nanosecond or longer laser pulses, graphitization propagates vertically into bulk layers, leading to the formation of diamond-graphite interfaces after the laser treatment. By contrast, with femtosecond (0.2-0.5 ps) laser pulses, graphitization of the surface occurs layer by layer, resulting in a clean diamond surface after the ablation. This atomistic picture provides an explanation of recent experimental observations.

We report the formation of highly oriented, uniform, and spherical nanoparticles of 3C–SiC as a result of Coulomb explosion during the interaction of near-infrared ultrafast laser pulses with 3C–SiC thin films grown on Si substrate. Experiments were performed at laser fluences well below the single shot, thermal modification threshold.

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