The capacity of optical fiber communications has grown exponentially since its implementation decades ago. Optical fiber amplifiers, wavelength division multiplexing, and coherent communications have all enabled discontinuous growth. Space division multiplexing is proposed as the next discontinuity. Here tens of modes rather than a single mode are utilized in the transmission. Random scattering due to index fluctuations within the optical fiber cause coupling among the modal channels thereby degrading signal transmission. Principal mode transmission overcomes this limitation. Here a set of modes arrive localized at the fiber output unscattered. We review this methodology as it relates to optical communication capacity, but also as it relates to light localization. We also review the characterization of these modes both theoretically and experimentally.

自几十年前实施以来，光纤通信的容量呈指数级增长。光纤放大器、波分复用和相干通信都实现了不连续的增长。空分复用被提议作为下一个不连续性。这里在传输中使用了数十种模式而不是单一模式。由于光纤内的折射率波动引起的随机散射导致模式通道之间的耦合，从而降低了信号传输。主模式传输克服了这个限制。这里有一组模式到达未散射的光纤输出处。我们回顾了这种方法，因为它与光通信容量有关，但也与光定位有关。