Performance analysis of a tandem of white-light fiber-optic interferometers

A white-light fiber-optic interferometric system composed of sensing and receiving interferometers separated with a dichroic-type linking interferometer was analyzed in order to determine the minimum group imbalance necessary to separate signal and noise patterns. For this purpose the analytical formulas for contrasts of the cross-interference patterns as well as the patterns produced by the sensing and receiving interferometers were derived. The contrast behavior was analyzed as a function of alignment at all coupling points and the dichroism of the linking interferometer. It is shown that the minimum group imbalance, which is the parameter responsible for temperature stability of the sensor, may be decreased to half for certain alignments.