Nanostructure processing by near-field with femtosecond laser excitation: process switching and SERS application

This paper describes two topics. (1): Nano-processing by near-field optics can fabricate nano-scale structures even with near-infrared 800 nmTi:saphire laser. New phenomena using particles, leading to a new nano-processing technique via plasmonics, even with the use of dielectric particles is reported. The physics of nano-hole fabrication process is switchable simply by the laser fluence. (2): ZnO nanorod arrays on Si (100) substrate were grown by pulsed laser deposition (PLD) method, and then coated with Au. Two samples of Au-coated nanorod arrays with different average diameters of 150 nm and 400 nm were prepared to investigate the size dependence of the surface enhanced Raman scattering (SERS). The diameter of the nanorods was well controllable by the substrate position during PLD. High SERS enhancement was observed from both Au-coated ZnO nanorod arrays. The Raman spectra of Rhodamine 6G (R6G) as low as 1 nM were measured with average diameter of 400 nm at an excitation wavelength of 532 nm.