Fabricating subwavelength dot-matrix surface structures of molybdenum by transient correlated actions of two-color femtosecond laser beams.

Two-dimensional matrix of subwavelength dot structures are directly generated on molybdenum surfaces by focusing two-color femtosecond laser pulses through an optical lens. In contrast to the traditional fabrication approaches, the spatial periodicities of such surface structures are demonstrated to rely on the time delay of two laser beams through transient correlation between their ultrafast dynamic processes, in spite of their different colors and polarizations. The structure orientations can be tuned effectively via the laser polarization. Discussion suggests a new possible flexible way towards the nanoscale sophisticated material processing for many potential applications.