Laser machining using temporally controlled ultrafast pulses

Summary form only given. This presentation describes a micromachining technique using temporally controlled amplified ultrafast laser pulses. The temporal control is achieved by modulating frequency components of the spatially dispersed ultrafast pulses. User-defined pulse bursts are synthesized, for which the pulse-to-pulse separation time, pulse energy, and pulse width are individually controlled. These pulse bursts are then focused on metal, semiconductor, and dielectric samples and the machining characteristics are noted. The experimental results show that there is a distinct effect of the pulse separation ranging from sub-picosecond to tens of picoseconds on the machining characteristics. The results of machining using ultrafast pulse bursts are correlated with the time scales of physical phenomena occurring during ultrafast laser matter interaction, including non-linear optical absorption, energy transfer, and the explosive type of phase transformation. Time-resolved experimental investigations of these processes are also performed to provide a better understanding of ultrafast laser machining using the pulse bursts.