A medical device, system, and method having a flexible shaft and a multi-core fiber within the flexible shaft. The multi-core fiber includes a plurality of optical cores dedicated for shape sensing sensors, and a plurality of optical cores dedicated for force sensing sensors. A tip assembly can comprise a tip electrode and a coupler comprising at least one fiber support tube center. A distal portion of the coupler can be coupled to a proximal portion of the tip electrode. The tip assembly can further comprise a multi-core fiber comprising a plurality of cores and a fiber support tube. A proximal portion of the fiber support tube can be coupled to the at least one fiber support tube center.
