Periodic ripple structures on silicon substrates induced by femtosecond laser at various scan modes

摘要

An 880-nm Ti:sapphire laser is used to induce ripple structures on silicon substrates. Single-oriented ripples, twice-overlapped/interlaced single-oriented ripples and single/double-oriented ripples with lattice structures have been obtained at five scan modes. The ripples may be formed by an intensity modulation which arises from the interference of the incident laser and the surface plasmon polaritons excited by the scattered wave of laser. The lattice structures are believed to be formed by intersecting truncation of two mutually perpendicular ripples. All the ripples are oriented in the direction perpendicular to the laser polarization vector and with a period smaller than the laser wavelength.