Phase Sensitive OTDR Strain Measurement Using Single Mode Operation in Multimode OM4 Fiber

We present the first realization of strain sensing in a multimode OM4 optical fiber using phase-sensitive optical time-domain reflectometry. We demonstrate that single mode operation in an OM4 fiber is achievable and allows the fiber strain to be measured in a distributed manner. The 4 km of OM4 fiber is effectively measured with 20 cm spatial resolution which proves that coherent Rayleigh scattering based techniques can be used to interrogate multimode optical fibers.