Chinese Optics Letters, Volume. 5, Issue s1, 122(2007)
Surface modification by localized surface plasmon polaritons excited by femtosecond laser pulse
Nanohole fabrication using near electromagnetic field enhancement in vicinity of gold particles is demonstrated. Gold spherical particles with the diameters of 40, 80 and 200 nm are deposited on substrate surfaces and irradiated by a 100-fs laser pulse at the wavelength of 800 nm. The enhanced near field results in substrate surface modification and nanohole formation under the particle. The applied laser fluence ranges from the values below the ablation threshold of the substrate material without particles to the values slightly above it in order to estimate its influence on the properties of the produced structures. The morphological changes on the surface of soda lime glass, Si, and Au, and the parameters of the produced nanostructures are analyzed by scanning electron microscope and atomic force microscope. The distribution of the near electric field is analyzed by a finite difference time domain simulation code. The produced structures are found to depend strongly on the properties of the substrate and laser parameters. In the case of the metal and semiconductor substrates, the electric field is localized in the vicinity of the contact point. In the case of glass substrate the electric field is spreading in an area larger than the particle size. The enhancement factor is about an order of magnitude lower than the case of using the silicon substrate. The results indicate that this method is capable of producing precise nanostructure of a variety of materials.
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Nikolay N. Nedyalkov, Tetsuo Sakai, Petar A. Atanasov, Minoru Obara, "Surface modification by localized surface plasmon polaritons excited by femtosecond laser pulse," Chin. Opt. Lett. 5, 122 (2007)