Ablation of silicon and ultrathin fibers using single femtosecond pulse

Abstract

We exploit the nonlinear multiphoton interaction of a few-cycle femtosecond (fs) pulse with viscoelastic microfibers in order to produce nanoscale grooves on its surface. The single fs pulse has been extracted from 1 kHz pulse train by double-shutter gating technique by placing two mechanical shutters in the beamline and simultaneously triggering them with a controlled delay. With adjustment of the time delay between two shutters, a small transmission window has been created to cleanly extract a single or desired number of pulses. We found that the single-pulse ablation threshold for microfiber is 1 J/cm 2 while for absorbing surfaces like crystalline Si is 0.01 J/cm2. Precise diffraction unlimited ablation of materials opens a route to process nanoscale waveguides, microfluidic devices to isolate cells or macro-molecules.