A medical device that includes a carrier member, one or more operative components disposed in the carrier member, an optical fiber at least partly disposed in the carrier member, and at least one fiber Bragg grating (FBG) sensor array associated with the optical fiber and disposed in the carrier member. The carrier member includes an insertion end and side walls that contact the subject's body during positioning of the carrier member in the subject's body. The at least one FBG sensor array measures contact forces at one or both of the insertion end and along the side walls of the carrier member during positioning of the carrier member in the subject's body. A multi-core optical fiber configured for use in a medical device for positioning in a subject's body is also provided. A system and method for guiding positioning of a medical device in a subject's body is also provided.

A fiber optic connector for terminating a hollow-core optical fiber is disclosed. The fiber optic connector includes a ferrule having a proximal end, a distal end, and at least one fiber bore extending therebetween for receiving the hollow-core optical fiber. The fiber optic connector further includes a terminus having a terminus body with a proximal end, a distal end, and a passageway therebetween, and a lens received in the passageway. The passageway is configured to receive the ferrule therein so that a terminal end of the hollow-core optical fiber is positioned between the proximal and distal ends of the terminus body. The lens is configured to be located distally of the ferrule when the ferrule is received in the passageway. A fiber optic cable assembly having such a fiber optic connector and a method of terminating a hollow-core optical fiber with such a fiber optic connector are also disclosed.