Direct writing of chiral and nonlinear plasmonic devices

Progress in miniaturization constitutes an enormous impetus for technical innovations in information technology, permeating all economic sectors. Future IT systems will rely on photons instead of electrons which triggers the need for nanoscale optical devices. Plasmonic nanostructures constitute a promising approach since their minimum geometric features are not restricted by the diffraction limit.

This project will focus on designing, fabricating and testing of three-dimensional nano devices based on plasmonic nano­structures. The proposed devices are a chiral circular polarization converter and a chiral all-optical converter, downscaling telecom light to visible light on-chip by second and third harmonic generation. Polarization sensitive waveguides will serve for in- and out-coupling from the near to the far-field. The envisaged footprint of the device prototypes will be smaller than 1 μm2, constituting a crucial step towards optical device miniaturization.

The device fabrication requires the combination of full geometric shape control with desired material properties. In this regard, direct writing with electrons is the optimum choice. While the focused electrons account for minimum structural features, the direct writing provides access to three dimensions in a single step. In combination with ion-beam based patterning, complex devices can be fabricated within one vacuum chamber. Since plasmonic systems require a metallic optical response with preferably low losses, deposited and patterned materials will be optimized concerning their optical response in the visible range. Materials and devices will be characterized with various spectroscopic techniques. Numerical simulations and analytical calculations constitute the backbone of the experiments.

This project is funded by the German Research Association (DFG) under grant no. HO 5461/3-1 and is carried out in close collaboration with the CoreLab Correlative Microscopy and Spectroscopy of Helmholtz-Zentrum Berlin.