New approach to the design of fiber optic devices based on Berry's topological phase

We present here the use of Berry's's topological phase for possible realization of fiber optic sensors and devices. Berry's phase is the phase change that can be effected on a light beam without changing the optical path length, but by changing the direction of propagation of light. This phase is not dependent on the material properties of the medium through which light is traveling and hence achromatic. A tunable reflectivity fiber loop mirror based on this phase is demonstrated.