Abstract

A new micromachining technique using user-defined trains of amplified femtosecond laser pulses is described. In this method, each output pulse of an amplified femtosecond laser system operating at 1 kHz is separated into a number of different pulses at desired energy levels and temporal separations ranging from 1 ps to 1 ns. Two techniques are used for pulse separation, one is based on an n-fold Michelson interferometer, and the other uses the pulse shaping technique which modulates the spatially separated frequency components of ultrafast pulses. These pulse bursts are then focused on metal, semiconductor and dielectric samples and the material removal characteristics are noted. The experimental results show that there is a distinct effect of the pulse separation on the machining characteristics. It is observed that, in some cases, using pulse bursts provides better material removal than the original pulses separated by 1 ms.

© 2003 Optical Society of America