Resonant-Plasmon-Assisted Subwavelength Ablation by a Femtosecond Oscillator

We experimentally demonstrate the use of subwavelength optical nanoantennas to assist a direct nanoscale ablation using the ultralow fluence of a Ti:sapphire oscillator through the excitation of surface plasmon waves. The mechanism is attributed to nonthermal transient unbonding and electrostatic ablation, which is triggered by the surface plasmon-enhanced field electron emission and acceleration in vacuum. We show that the electron-driven ablation appears for both nanoscale metallic as well as dielectric materials. While the observed surface plasmon-enhanced local ablation may limit the applications of nanostructured surfaces in extreme nonlinear nanophotonics, it, nevertheless, also provides a method for nanomachining, manipulation, and modification of nanoscale materials. Collateral thermal damage to the antenna structure can be suitably avoided, and nonlinear conversion processes can be stabilized by a dielectric overcoating of the antenna. © 2018 American Physical Society.