Intra- and inter-wafer characterization of waveguide propagation loss and reflectivity

In silicon photonics, due to the increasing complexity of the device designs and the increasing density of the functions integrated on a single circuit, the precise characterization of the building blocks has become essential in order to assess the quality of the fabrication outcomes. As waveguides are the fundamental building block of photonic integrated circuits, its accurate characterization is very important to evaluate the quality of all passive elements. In this paper the characterization of two very important parameters, namely waveguide propagation loss and waveguide sidewall reflectivity, are reported for waveguides utilized inside a microring-based silicon photonic network-on-chip. Using a recently proposed method based on undercoupled all-pass microring structure, the two parameters from five differently positioned chips in two different wafers are measured in order to investigate the intra- and inter-wafer variations. Precise measurements alloalloww to define range of values and variations for these two parameters in photonic network-on-chip.