ABSTRACT
Single-mode fiber and gradient-index fiber, though, are more difficult to make and require stricter fabrication controls. The literature is full of papers on making multimode step index fiber but gradient-index and single-mode fibers with active core materials have only appeared in the literature in the 1990s. While this is not yet a mature technology, the potential for high value-added products makes these high-bandwidth fibers attractive for future development. Potential devices include optical switching, fiber lasers, and optical amplifiers.
