Abstract

A major attraction of optical fibers for the sensor system is the possibility of passive sensing, that is, sensing without the use of electrical components In the sensor head. The frequency modulated continuous wave technique (FMCW) is one method of interrogating an interferometric sensor which does not require use of phase modulators or frequency shifters at the sensor head. The technique has been shown capable of determining the absolute imbalance of an interferometer^1,2 or with different signal processing to be suitable for determining very small phase changes in the interferometer arms.^3,4 The technique may also be used for multiplexing sensors, and in this paper we consider the design of a multiple sensor system in which the sensors are multiplexed using this frequency modulation technique.

© 1985 Optical Society of America