  While silicon photonics has leveraged the nanofabrication tools and
techniques from the microelectronics industry, it has also inherited the
metrological methods from the same. Photonics fabrication is inherently
different from microelectronics in its intrinsic sensitivity to 3D shape and
geometry, especially in a high-index contrast platform like
silicon-on-insulator. In this work, we show that electrical resistance
measurements can in principle be used to infer the geometry of such
nanophotonic structures and reconstruct the micro-loading curves of foundry
etch processes. We implement our ideas to infer 3D geometries from a standard
silicon photonics foundry and discuss some of the potential sources of error
that need to be calibrated out to improve the reconstruction accuracy.
