Electrical & Computer Engineering, Department of


Date of this Version



Optics Express 20:19 (2012), pp. 21505 - 21511


Copyright © 2012 Optical Society of America. Used by permission.


This study reveals that the periods, ablation areas and orientations of periodic surface structures (ripples) in fused silica can be adjusted by using designed femtosecond (fs) laser pulse trains to control transient localized electron dynamics and corresponding material properties. By increasing the pulse delays from 0 to 100fs, the ripple periods are changed from ~550nm to ~255nm and the orientation is rotated by 90°. The nearwavelength/subwavelength ripple periods are close to the fundamental/second-harmonic wavelengths in fused silica respectively. The subsequent subpulse of the train significantly impacts free electron distributions generated by the previous subpulse(s), which might influence the formation mechanism of ripples and the surface morphology.