Periodic nanoscale structures on polyimide surfaces generated by temporally tailored femtosecond laser pulses

A strong influence of different pulse durations and double pulse delay times on the formation of periodic surface structures on polyimide were observed employing ultrashort laser pulses tailored on a sub-picosecond and picosecond time scale. Multi-photon, defect-related excitation mechanisms and thermal expansion of the polymer lattice correlated to a loss of long range order and polarisation memory were considered. Laser pulse duration and double pulse delay time strongly affect the formation of periodic surface structures on polyimide by employing ultrashort laser pulses tailored on a sub-picosecond and picosecond time scale.