Nonlinear Laser Lithography
Start date: Jun 1, 2014,
End date: May 31, 2019
"Control of matter via light has always fascinated humankind; not surprisingly, laser patterning of materials is as old as the history of the laser. However, this approach has suffered to date from a stubborn lack of long-range order. We have recently discovered a method for regulating self-organised formation of metal-oxide nanostructures at high speed via non-local feedback, thereby achieving unprecedented levels of uniformity over indefinitely large areas by simply scanning the laser beam over the surface.Here, we propose to develop hitherto unimaginable levels of control over matter through laser light. The total optical field at any point is determined by the incident laser field and scattered light from the surrounding surface, in a mathematical form similar to that of a hologram. Thus, it is only logical to control the self-organised pattern through the laser field using, e.g., a spatial light modulator. A simple wavefront tilt should change the periodicity of the nanostructures, but much more exciting possibilities include creation of patterns without translational symmetry, i.e., quasicrystals, or patterns evolving non-trivially under scanning, akin to cellular automata. Our initial results were obtained in ambient atmosphere, where oxygen is the dominant reactant, forming oxides. We further propose to control the chemistry by using a plasma jet to sputter a chosen reactive species onto the surface, which is activated by the laser. While we will focus on the basic mechanisms with atomic nitrogen as test reactant to generate compounds such as TiN and SiN, in principle, this approach paves the way to synthesis of an endless list of materials.By bringing these ideas together, the foundations of revolutionary advances, straddling the boundaries of science fiction, can be laid: laser-controlled self-assembly of plethora of 2D patterns, crystals, and quasicrystals alike, eventually assembled layer by layer into the third dimension -- a 3D material synthesiser."
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