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 f emtosecond laser pulses (wavelength similar to 800 nm). A variety of period ic nanostructures from a one-dimensional wire array to two-dimensional arra ys of holes or islands were formed by changing the energy density and the i ncidence 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 f or holes. Laser-driven microexplosions occurring within the microcylindrica l-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 enco de these periodic structures, which are applicable to emerging nanostructur ed devices such as photonic crystals and quantum dot or wire arrays. (C) 20 01 American Institute of Physics.