Nonlinear optical phenomena which dominate the interaction of tightly focused femtosecond laser beams with materials are discussed. Different femtosecond laser based techniques for material processing such as laser ablation, two-photon photo-polymerization, and material surface nano-structuring are described. For the computer controlled micro-processing of materials, near-infrared Ti:sapphire femtosecond lasers, with nano-Joule/micro-Joule pulse energy, were coupled with direct laser writing workstations. Laser fabricated micro-nanostructures and their applications are presented.
Metamaterials and photonic crystals are presented as the main approaches to achieve artificial negative refractive materials. Alone or associated with lithography techniques, femtosecond laser constitutes a potential tool for manufacturing negative refractive materials in the range from GHz to optical frequencies. Multi-photon photopolymerization of transparent materials and micro/nano-machining of metallic thin films are promising methods to obtain negative refractive photonic crystals and, respectively, metamaterials. Preliminary experiments of thin-film micro-machining using a femtosecond oscillator-amplifier laser are described. Further methods to improve the femtosecond laser machining are proposed.