At low costs: Study on optical propagation losses of silicon waveguides fabricated by electron beam lithography

Abstract

In this work a novel electron beam lithographic exposure technique suitable for the fabrication of low-loss nanophotonic waveguide structures based on silicon-on-insulator substrate material is presented. This technique utilizes a multi pass exposure approach; hence each feature of the waveguide structures is not only exposed once as in conventional electron beam lithography (EBL) but multiple times. The benefit of this technique lies in a significant reduction of the optical propagation losses (OPLs) of fabricated waveguides. For a multi pass exposure with four exposure passes a reduction of OPLs by more than 1.5dB/cm has been achieved compared to a fabrication based on conventional EBL techniques. At the same time, despite being based on a multi pass approach, the multi pass exposure technique comes at surprisingly low costs in terms of additional exposure time, as the total exposure time including all overhead is only increased by less than 20%.