Precise waveguide loss extraction using 300-mm wafer-level OFDR for optical process control monitoring

The propagation loss for silicon waveguides extracted by wafer-level OFDR was verified by comparing it with the cutback method. As the results of evaluating for 256 waveguides with a width of 420-480 nm, the OFDR and cut-back methods found to provide almost the same loss with a correlation coefficient of 0.96, indicating the applicability of OFDR to manufacturing monitoring.