Reconfigurable Near‐field Enhancement with Hybrid Metal‐Dielectric Oligomers

Tailoring of the near‐field properties of the nanostructures is a significant task for the control of radiation of nanoscale light sources as well as for sensing applications. Generally, this task is solved in plasmonic oligomers on the fabrication step by the choice of geometry or by controlling the excitation light during the experiments. Here, the pronounced modification of the near‐field pattern in hybrid gold‐silicon oligomers by femtosecond laser reshaping by visualizing it with aperture‐type near‐field optical microscope is demonstrated. This effect correlates with a moderate red‐shift of the broadband magnetic dipole resonance of the structure that occurs upon reshaping the gold component of the oligomers. The proposed all‐optical near‐field reconfiguration approach makes hybrid oligomers a promising platform for on‐demand engineering of local field enhancement in metadevices for data recording and sensing.