Modal power distribution in short reach optical communications using step-index-type multimode optical fibers

In an optical communication system using Step Index type Multi-Mode optical Fiber (SI-MMF), the propagating modal power distribution (MPD) in the fiber is strongly influenced by the transmission characteristics. In most cases the MPD launched from the optical transmitter is significantly transformed before reaching the receiver due to a number of factors, i.e. mode conversion and mode dispersion along the fiber and the various components inserted in the optical path. In order to secure the minimum received optical power and desired bandwidth at the receiver, we propose using the concept of “Total MPD management” for all interfaces in the transmission line. To implement this concept, a method of specifying requirements to the device side from the specifications on the system side is needed. Although rapid changes in MPD arise, especially in SI-MMFs, there is no universal means of quantifying this. In this paper, we define a simple quantification method for MPD which we have named the “encircled angular flux (EAF)”, and which can be used to accurately design optical systems (FFP-based). Moreover, this EAF acts as a fundamental parameter for the design, mounting and evaluation of optical components and can provide the specifications required for connecting to a network. We expect the use of “Total MPD management” and “IEC standardization” will generate interest in related institutions and suppliers worldwide.