A dual-mode active and passive gimbaled optical system including a mechanism for coupling an optical signal from an off-gimbal active-mode source into the on-gimbal passive-mode optical path. One example of the system includes a passive off-gimbal detector assembly configured to image emissive electromagnetic radiation from a viewed scene, and a receiver-path optical assembly, including on-gimbal objective optics, that directs the electromagnetic radiation to the off-gimbal detector assembly. The system further includes an off-gimbal active source that generates an optical signal, a gimbal bearing assembly that supports rotation of the gimbal and includes a centrally-located output ferrule mated to an optical fiber that transports the optical signal from the active source to the output ferrule, and an on-gimbal optical coupling element that receives the optical signal from the output ferrule and couples the optical signal into the receiver optical path to direct the optical signal toward the on-gimbal objective optics.