  The polarization of light conveys unique information that can be exploited by
crucial applications. The bulky and costly discrete optical components used in
conventional polarimeters limit their broad adoption. A compact, low-cost
polarimeter would bring this functionality into a myriad of new scenarios and
revolutionize its exploitation. Here we present a high-performance, full-Stokes
polarimeter on a silicon chip. A surface polarization splitter and on-chip
optical interferometer circuit produce the analysis matrix of an optimally
conditioned polarimeter. This solid-state polarimeter is a system-on-a-chip
with exceptional compactness, stability, and speed that could be used singly or
in integrated arrays. Large arrays can increase the speed and resolution of
full-Stokes imaging; therefore, our design provides a scalable polarimeter
solution.
