“…When considering high capacity, short-reach data-center applications however, where both cost and power consumption need to be kept as low as possible, the use of MIMO-less direct detection is imperative, and this imposes stringent requirements on the tolerable cross-talk levels among the transmitted modes. Recently, the use of elliptical (multi-) core FMF has been proposed as a means to guarantee negligible mode coupling even between modes of the LP 11 mode group that are normally degenerate [2][3][4][5]. Notably, MIMO-less SDM transmission using three-spatial-modes (LP 01 , LP 11a and LP 11b ) at 1.3 m and two-spatial-modes (LP 01 and LP 11a ) at 1.5 m was demonstrated in a (sub) km-long FMF with a core-ellipticity of about 40% [2].…”