Low-loss silicon-on-insulator waveguides

The aim of photonic integrated circuits (PICs) is to realise a variety of different optical components on a single chip. Silicon-on-insulator technology is a promising candidate for realising PICs with advanced properties. In this work, a fabrication process based on dry silicon etching was developed to produce SOI optical waveguides. The base for the waveguide fabrication was a 10 cm diameter SOI wafer with a 10 µm thick device layer. The silicon etching was done with an inductively coupled plasma type reactive ion etcher. High propagation loss measurement accuracy was achieved by using a long waveguide, which diminishes the effect of the fiber-coupling losses. A 114 cm long waveguide was fitted on the 10 cm SOI wafer in a form of a spiral. As a result, propagation loss 0.13 ± 0.02 dB/cm was measured at 1550 nm for the fundamental mode in a rib-type SOI waveguide.