Photonic lantern as mode multiplexer for multimode optical communications

The majority of optical fiber technology developments in the applied sciences have arisen from developments in telecommunications. However, the photonic lantern is one of several devices that arose to solve problems in astronomy. Interestingly, these devices are now being extensively used in multimode optical telecommunications research and are likely to find commercial use in the next few years. A photonic lantern allows for a low-loss transformation of a multimode system into a discrete number of single-mode ones and vice versa, thus, enabling their use as mode multiplexers/demultiplexers in Space Division Multiplexing (SDM). Further, it provides seamless integration with the rest of single-mode photonic technologies in telecommunication systems. In this paper, we will discuss the theory and function of the photonic lantern, along with several different variants of the technology needed for their use in SDM communications, focusing on the fiber-bundle photonic lanterns type. We will also discuss some of its current and future applications.