Double surface plasmon resonances obtained with Bessel-beam-written nanoslits arrays

Femtosecond laser ablation with Bessel beam profile can yield high quality structures on metal thin films at nanoscale [1]. By adjusting the laser fluence one can control size of ablated structures. Moreover, resolution can go beyond the diffraction limit when the laser energy is adjusted around the ablation threshold [2]. Advantages of using diffraction-free Bessel beams bring us to ablate 125 nm-wide stripes. In this work, we demonstrate potential of Bessel-beam nanofabrication method and optical properties of created structures for plasmonic applications. Nanoslit arrays are structured through ablation by femtosecond laser with Bessel Beams on 25 nm-thick Gold (Au) film evaporated on Fused Silica substrate. We fabricated stripes at nanoscales with different periodicities (p=500 nm, 790 nm and 810 nm). Since the fabrication method does not require high cost focusing optics or any special sample preparation, process is straightforward and well candidate to compete against standard lithographical methods.