Spatial domain multiplexing (SDM), also known as space division multiplexing, adds a new degree of photon freedom to existing optical fiber multiplexing techniques by allocating separate radial locations to different channels of the same wavelength as a function of the input launch angle. These independent MIMO channels remain confined to their designated locations while traversing the length of the carrier fiber owing to helical propagation of light inside the fiber core. As a result, multiple channels of the same wavelength can be supported inside a single optical fiber core, thereby allowing spatial reuse of optical frequencies and multiplication of fiber bandwidth. It also shows that SDM channels of different operating wavelengths continue to follow an output pattern that is based on the input launch angle. As a result, the SDM technique can be used in tandem with wavelength division multiplexing (WDM), to achieve higher optical fiber bandwidth through increased photon efficiency and added degrees of photon freedom. This endeavor presents the feasibility of a hybrid optical fiber communication architecture in which the spectral efficiency of the combined system increases by a factor of "n" when each channel of an "n" channel SDM system carries the entire range of WDM spectra. © 2016 Society of Photo-Optical Instrumentation Engineers (SPIE).
Murshid, S. H., Lovell, G. L., Hridoy, A., Parhar, G., Chakravarty, A., Alanzi, S., & Chowdhury, B. (2016). Wavelength independency of spatially multiplexed communication channels in standard multimode optical fibers. Optical Engineering, 55(8)