Hybrid femtosecond laser three-dimensional micro-and nanoprocessing: a review

Currently, laser is an essential tool for processing and synthesis of diverse materials and thereby is widely employed for practical use. Prof. Sugioka’s team aims at research and development of advanced laser processing which realizes low environmental load, high quality, high efficiency fabrication of materials by using ultrafast lasers such as femtosecond and picosecond lasers. The developed techniques include three-dimensional (3D) micro/nanofabrication, high aspect ratio machining, and synthesis of new materials, which are applied for fabrication of biochips and high function photonic and electronic micro/nanodevices. Among them, 3D micro/nanofabrication is reviewed in this paper. The extremely high peak intensity associated with ultrashort pulse width of femtosecond lasers enabled inducing nonlinear multiphoton absorption in materials that are transparent to the laser wavelength. More importantly, focusing the fs laser beam inside the transparent materials confined the nonlinear interaction to within the focal volume only, realizing 3D micro/nanofabrication. This 3D capability offers three different processing schemes for use in fabrication: undeformative, subtractive, and additive. Furthermore, a hybrid approach of different schemes can create much more complex 3D structures and thereby promises to enhance the functionality of the structures created. Thus, hybrid fs laser 3D microprocessing opens a new door for material processing.