On-Wafer Optical Loss Measurements Using Ring Resonators With Integrated Sources and Detectors

We demonstrate for the first time a fully integrated test structure dedicated to on-wafer propagation loss measurement. An integrated light source is used in combination with a resonant cavity and a full absorbing detector. It is fabricated in a multi project wafer run in an InP based foundry process. The probing of the integrated light source and detector with electrical signals avoids the reproducibility issues and time-overhead associated with high-precision optical alignment. The measurement accuracy, estimated to be ~±0.2, the compact footprint (~1.5 mm2), and the simple and fast measurement procedure make this approach an ideal candidate for the future characterization of propagation losses in both research and manufacturing environments.