Dual-sensor technique for extending the dynamic range of a fiber-optic interferometric sensor.

A sensor consisting of two fiber-optic interferometers of slightly different sensitivities can offer both high sensitivity and a wide dynamic range when the phase difference between the two interferometer outputs is used to identify the order of the fringe from either interferometer output. This technique is demonstrated with a polarimetric temperature sensor utilizing two different lengths of stress-induced birefringent fibers as sensing elements.