Multiplexed sensor of dynamic strains using photorefractive wave mixing in the reflection geometry

摘要

We propose a novel multiplexing system for sensing of dynamic strains in which several multimode optical fibers are used as sensitive elements. In the proposed configuration several object beams emerged from different multimode fibers are mixed in one crystal altogether with a common reference beam, which is directed from the opposite face of the sample. The geometry of the light-beam interaction inside the crystal assures low cross-talk between the measuring channels in spite of the fact that all the object beams are mutually coherent since they originate from one and the same laser. We have found that the crosstalk is much smaller than the noise level of any channel, which relates to instability of the polarization state of the speckle field emerged from the fibers.