Coherence multiplexing of fiber-optic pressure and temperature sensors based on highly birefringent fibers

In this paper, we present several coherence-based configurations of sensor systems that have been designed and studied specifically for multiplexing o f white-light interferometric pressure and temperature transducers based on highly birefringent optical fibers. The first discussed is a serial system that may be composed of up to four pressure (range 0-20 MPa) and temperatu re (range - 50 degrees C-+50 degrees C) sensors powered by a single broadba nd laser source. An electronically scanned interferometer based on a Wollas ton prism with a step-delay line and a CCD array was used as a decoding uni t, To increase the number of multiplexed sensors we also proposed a mixed s erial-parallel configuration in which two serially connected sensors for me asuring pressure and temperature are further arranged in parallel branches powered by several independent sources, The absolute system accuracy is abo ut 0.5% of full scale. In addition to the full characterization of all mult iplexed pressure sensors against a primary pressure standard, system respon se to fast temperature changes, to connecting additional cables, to input-o utput replacing, and to exchanging sources is also presented.