A proposal for linear and nonlinear discrete and distributed sensing of mechanical strain with graphene-decorated optical fibers

We propose a novel optical sensor for the linear and nonlinear measurement of discrete and distributed mechanical strain, capable of discriminating longitudinal (traction) from transverse (compression) forces. The sensor is based on a standard single-mode optical fiber whose cladding is removed and its core is coated with graphene. The transduction scheme works by monitoring changes experienced in the linear absorption and the nonlinear coefficient of the graphene-decorated fiber when subject to said forces. Further, we show that the distributed sensing of strain can be easily performed by means of conventional optical time-domain reflectometry. Last, we introduce a two-piece sensor design capable of discriminating the type of strain by straightforward loss measurements.