US Patent 12130394 Fiber optic interrogation system

A sensing optical fiber includes multiple waveguides or cores to allow sensing of multiple measurands using a single fiber. The fiber can be a dual clad fiber having a single mode core and a multi-mode core disposed radially or circumferentially about the single mode core. A dual clad fiber coupler couples source light from a DAS interrogator and a DTS interrogator into the dual clad fiber in use.