Nano-periodic structure formation on titanium thin film with a Femtosecond laser

概要

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Periodic nanostructures were observed on the Ti thin film surface after irradiation with a focused beam of femtosecond Ti:sapphire laser. It has been found which, on the ablated Ti thin film surface, the linearly polarized femtosecond laser pulses produced arrays of ripple-like periodic nanostructures that were oriented to the direction parallel to the laser polarization, and a net-like nanostructure was fabricated on the surface of Ti thin film by the technique of two linearly polarized femtosecond laser beams with orthogonal polarizations ablating material alternately. The period of self-organized ripple-like nanostructures can be controlled by the pulses energy and the number of irradiated pulses. The result suggests that the formation of periodicity can be attributed to the excitation of surface Plasmon polarizations which induce initial period distribution of the electron plasma concentration orientation parallel to the light polarization on the surface layer. The estimated field period was in general accord with the observed size of nanostructures.