DIRECT OBSERVATION OF BERRYS TOPOLOGICAL PHASE BY USING AN OPTICAL-FIBER RING INTERFEROMETER

This paper describes a simple interferometric arrangement, which allow s a direct observation of Berry's topological phase in optical fibers, The interferometer consists of a single mode, low birefringent fiber ring that involves a non-coplanar path (a helix). The fringe shift obs erved by changing the helix pitch permits the measurement of the geome trical phase.