O-FIB: Far-field-induced near-field breakdown for direct nanowriting in an atmospheric environment
(PHYSorg.com Physics)

Lasers are becoming one of the dominant tools in current manufacturing industry. Much effort has been devoted to improving processing accuracy, and spatial resolutions as low as micrometers have been achieved in laser cutting, welding, marking and stereolithography in an atmospheric environment. The femtosecond laser (fs-laser) is a particularly promising approach from this point of view, in addition to its three-dimensional (3-D) processing capability and broad-spectrum material usability. Super-diffraction-limited feature sizes at a level of tens of nanometers based on multiphoton absorption thresholding, shrinkage and stimulation emission depletion effects have also been realized in fs-laser induced photocuring of polymers, which unfortunately are not applicable to solid materials. Optical near-field techniques provide an alternative super-resolution scheme by localizing light fields to nanometer scales with the physical shapes of sharp tips, tiny apertures, nanoparticles and small protrusions. Nevertheless, these approaches often rely on heavy movement and alignment systems to maintain precise probe-substrate spacing for practical fabrication/patterning throughput due to the evanescent nature of the near field.