A folded configuration of a fiber Sagnac-based sensor array

We introduce a folded configuration of a previously described Sagnac interf erometer-based sensor array. It is shown that the folded configuration less ens the detrimental effects of distributed phase modulations in the delay c oil while also reducing the required delay coil length by a factor of 2. A prototype two-sensor array was constructed and measured to perform accordin g to theory, exhibiting a phase sensitivity of roughly 3 mu rad/root Hz in a single-pert detection configuration and 0.8 mu rad/root Hz in a balanced detection configuration. The desensitization of the delay coil was measured to agree with theory. (C) 2000 Academic Press.