Focused ion beam nano-structuring of photonic Bragg gratings in Al2O3 waveguides

Focused ion beam (FIB) etching is receiving increasing attention for the fabrication of active integrated optical components such as waveguide amplifiers and lasers. Si-technology compatible low-loss Al2O3 channel waveguides grown on thermally oxidized silicon substrates have been reported recently. We used FIB milling for reflection grating definition on Al2O3 channel and ridge waveguides. Structural optimization has been achieved by experimentally adjusting FIB patterning parameters such as ion current, dwell time, loop repetitions, scanning strategy, and applying a top metal layer for reducing charging effects and sidewall definition improvement. Optical properties of these devices are currently being studied.