Large-mode-area, multimode, hybrid optical fibers and devices using same

A large mode area optical fiber is configured to support multiple transverse modes of signal radiation within its core region. The fiber is a hybrid design that includes at least two axial segments having different characteristics. In a first axial segment the transverse refractive index profile inside the core is not radially uniform being characterized by a radial dip in refractive index. The first segment supports more than one transverse mode. In a second axial segment the transverse refractive index profile inside the core is more uniform than that of the first segment. The two segments are adiabatically coupled to one another. Illustratively, the second segment is a terminal portion of the fiber which facilitates coupling to other components. In one embodiment, in the first segment M 1 2 > 1.0, and in the second segment M 2 2 > 1.0 and M 2 2 ~ 1.0. In another embodiment, the optical fiber is coupled to a fiber stub.