OPTICAL FIBER AMPLIFIERS: Few-mode fiber amplifiers assist spatial-division multiplexing

摘要

To increase the transmission capacity of a single optical fiber, an alternative to dense wavelength-division multiplexing (DWDM) called spatial-division multiplexing (SDM) has been proposed using either multicore optical fibers or few-mode fibers (FMFs). The FMFs are a type of fiber with a core area large enough to transmit parallel data streams in a few independent spatial modes. Ideally, the capacity of an FMF is proportional to the number of modes. However, to extend transmission distance, few-mode fiber amplifiers are required that-unlike those used in free-space optical communication and high-power laser applications-have controllable mode-dependent gain to ensure all SDM channels are optimized.