Versatile direct laser writing of non-photosensitive materials using multi-photon reduction-based assembly of nanoparticles

Versatile direct laser writing (DLW), not limited by material photosensitivity, offers opportunities for fundamental and technological innovation for micro-/nanofabrication in integrated photonics, electronics and material science. Although DLW has high potential in micro-/nanodevice fabrication, material choice suffers an intrinsic limitation: DLW cannot be applied to non-photosensitive materials. We describe a newly discovered rapid-assembly phenomenon of fine particles based on femtosecond laser multi-photon-reduction in solution. This phenomenon allowed the writing of micropatterns with thick clad layers filled with nanoparticles. We wrote continuous patterns by moving the laser focus even in the case of non-photosensitive material such as SiO(2). By transcending the strict material limitation, this novel laser writing process promises to be a powerful tool in a variety of scientific fields.