Formation of periodic metal nanowire grating on silica substrate by femtosecond laser irradiation

We demonstrate a method to fabricate isolated metal nanowire gratings on a substrate by using femtosecond (fs) laser. By irradiating fs laser pulses with 500-fs pulse duration, 800 nm in central wavelength at a pulse repetition rate of 1 kHz, to platinum thin films with thicknesses of 48 and 576 nm deposited on fused silica substrates, two different periodicities of ripple structure were formed: the periodicity less than half of the laser wavelength and that comparable to the laser wavelength. Scanning electron microscopy and cross-sectional imaging after milling with focused ion beam revealed that the periodic aligned platinum structures were formed on the surface of a fused silica substrate. Energy-dispersive X-ray spectroscopy and atomic force microscopy supported the demonstration of nanowire gratings in which platinum and fused silica were alternately and periodically exposed. The results demonstrate the formation of isolated platinum nanowire gratings. The presented technique has potential to be used as a simple and high-throughput process for fabrication of plasmonic nanostructures for optical, electrical, and biomedical devices.