Abstract: A glass optical fiber includes multiple cores fused into a single fiber. The new optical fiber is coherent, in the sense that the cores maintain their relative position with respect to each other within the fiber throughout the length of the fiber. That is, a core having specific radial and angular positions at one end of the fiber will have the same radial and angular positions throughout the fiber, including at the fibers opposite end. In one aspect of the invention the fiber presents a circular cross section, in another it presents an elliptical cross section of greater eccentricity to ease the task of orienting the cores within the fiber for connection to signal sources, other fibers, integrated optic devices, receivers and other optical components. An orienting core may suitably be included in the fiber to further assist in orienting the fiber end. In manufacturing the new optical fiber, a silica tube is stuffed with core canes.