Generation of New Nanomaterials by Interfering Femtosecond Laser Processing

ABSTRACTNew nanomaterials such as nanobump array, nanomesh, nanobelt were generated from thin film processed by interfering femtosecond laser beams. Metallic single- or multi-layered film deposited on a silica substrate was used as a raw thin film. With four interfering femtosecond laser beams, a conical nanobump arrayed in a matrix was generated with single laser shot. As the femtosecond laser fluence increased, the nanobump increased in diameter and height, and a bead was found at the top. Moreover, with three or two interfering femtosecond laser beams, ellipsoidal or linear nanobump array was generated. As an application of a conical nanobump array, field emission from the nanobump array was demonstrated, and the I-V characteristics were measured. On the other hand, with much higher fluence and four interfering femtosecond laser beams, a nanohole array was generated. A nanomesh was also generated from the nanohole array by exfoliating the film. A grating was generated with two interfering femtosecond laser beams, and nanobelts were generated from the grating by exfoliating. Bimetallic nanobelt was also generated from multi-layered thin film.