Interferometry without beam splitters — a sensitive technique for spinor phases

Abstract

We report some optical interference experiments that measure geometrical phase changes arising from polarization transformations. In these experiments, the two interfering beams travel exactly the same path in space without encountering any beam splitter or mirror, yielding striking agreement with theoretical predictions even in the regime where the predicted phase changes are highly nonlinear and switch sign for a small change in the experimental parameters, a characteristic feature of such phases.