  While ultrafast laser welding is an appealing technique for bonding
transparent workpieces, it is not applicable for joining silicon samples due to
nonlinear propagation effects which dramatically diminishes the possible energy
deposition at the interface. We demonstrate that these limitations can be
circumvented by local absorption enhancement at the interface thanks to
metallic nanolayer deposition. By combining the resulting exalted absorption
with filament relocation during ultrafast laser irradiation, silicon samples
can be efficiently joined. Shear joining strengths >4 MPa are obtained for
21-nm gold nanolayers without laser-induced alteration of the transmittance.
Such remarkable strength values hold promises for applications in
microelectronics, optics, and astronomy.
