Abstract
Spatial domain multiplexing (SDM) is a system that allows multiple channels of light to traverse a single fiber, utilizing
separate spatial regions inside the carrier fiber, thereby applying a new degree of photon freedom for optical fiber
communications. These channels follow a helical pattern, the screen projection of which is viewable as concentric rings
at the output end of the system. The MIMO nature of the SDM system implies that a typical pin-diode or APD will be
unable to distinguish between these channels, as the diode will interpret the combination of the SDM signals from all
channels as a single signal. As such, spatial de-multiplexing methods must be introduced to properly detect the SDM
based MIMO signals. One such method utilizes a fiber consisting of multiple, concentric, hollow core fibers to route
each channel independently and thereby de-mux the signals into separate fibers or detectors. These de-mux fibers consist
of hollow core cylindrical structures with beveled edges on one side that gradually taper to route the circular, ring type,
output energy patterns into a spot with the highest possible efficiency. This paper analyzes the beveled edge by varying
its length and analyzing the total output power for each predetermined length allowing us to simulate ideal bevel length
to minimize both system losses as well as total de-mux footprint. OptiBPM simulation engine is employed for these
analyses.
