Expected Noise Levels For Interferometric Sensors Multiplexed Using Partially Coherent Light

A method for multiplexing interferometric optical sensors is reviewed, and theoretical results are presented which predict the phase sensitivity of sensors multiplexed using this method. The multiplexing technique--"coherence multiplexing' is based on the use of a source whose coherence length is short compared to most system optical path length differences. The use of a single-mode semiconductor laser diode source typically leads to a min-imum detectable phase on the order of a milliradian per VHz. Small improvements result from the use of a noise-canceling balanced detection scheme. Sensitivity in the microradian per VHz regime might be achieved through the use of a shorter coherence length source such as a superluminescent diode.