Silicon-metal and silicon-silicon ultrafast laser welding with domesticated filaments

We demonstrate for the first time ultrafast laser welding in the silicon-metal and silicon-silicon configurations, with focused infrared picosecond pulses. This achievement relies on accurate characterizations of filamentation in silicon with nonlinear propagation imaging. In the silicon-metal configuration, precompensating for the nonlinear focal shift prior to the welding yields bonding strengths > 1 MPa. By combining this filament relocation technique with metallic nanolayer deposition at the interface to exalt the energy deposition, similar bonding strength values are obtained in the silicon-silicon configuration.