PROSPECTS FOR NONLINEAR FORWARD-SCATTER DISTRIBUTED OPTICAL-FIBER SENSING

Optical fibres offer special advantages for fully-distributed sensing. They comprise an essentially one-dimensional measurement medium which can be used to provide the spatial distribution of a variety of measurands within large structures. To date, most fully-distributed optical-fibre sensor systems have relied on backscatter, OTDR, techniques. This paper proposes an alternative, forward-scatter approach; it utilises non-linear interactions between counter-propagating beams in optical fibres. This latter approach offers possibilities for a significant improvement in performance for such sensors. Some possible systems based on this approach are described and preliminary experimental results are presented.