Spatial Domain Multiplexing (SDM) is a novel optical fiber multiplexing technique where multiple channels of the same
wavelength are launched at specific angles inside a standard step index multimode carrier fiber. These channels are
confined to specific locations inside the fiber and they do not interfere with each other while traversing the length of the
fiber. Spatial filtering techniques are employed at the output end to separate, route and process the individual channels.
These skew ray channels inside the SDM system follow a helical trajectory along the fiber. The screen projection of the
skew rays resembles a circular polygon. A ray theory based mathematical model of the SDM system is presented and
simulated as well as experimental data is compared to the model predictions. This ray theory model utilizes launch point,
input incidence angle, and point of incidence on fiber to explain the behavior of the individual channels. Thus the vector
approach to propagation allows us to predict the effects of pulse spreading in the SDM system. The results showed that
the skew ray trajectory is sensitive to input incidence angle. Similarly changing the launch point, while maintaining the
angle of incidence constant with the z axis, can drastically affect the skew ray trajectory.
Spatial Domain Multiplexing (SDM) is a novel technique in optical fiber communications. Single mode fibers are used
to launch Gaussian beams of the same wavelength into a multimode step index fiber at specific angles. Based on the
launch angle, the channel follows a helical path. The helical trajectory is explained with the help of vortex theory. The
electromagnetic wave based vortex formation and propagation is mathematically modeled for multiple channels and the
results are compared against experimental and simulated data. The modeled output intensity is analyzed to show a
relationship between launch angle and the electric field intensity.