Periodic nanostructure array in crossed holographic gratings on silica glass by two interfered infrared-femtosecond laser pulses

Two cross-superposed holographic gratings were encoded on silica glass by femtosecond laser pulses (wavelength similar to 800 nm). A variety of periodic nanostructures from a one-dimensional wire array to two-dimensional arrays of holes or islands were formed by changing the energy density and the incidence angle of the irradiation laser beams. The smallest dimensions were a width of similar to 15 nm for wires and a diameter of similar to 20 nm for holes. Laser-driven microexplosions occurring within the microcylindrical-lens array created by the first laser pulse are suggested as a mechanism for the formation of these structures. Only two pulses are required to encode these periodic structures, which are applicable to emerging nanostructured devices such as photonic crystals and quantum dot or wire arrays. (C) 2001 American Institute of Physics.