In the present paper, polymer optical fibers of wide bandwidth in high speed optical communication systems are deeply studied over wide ranges of the affecting parameters. The phenomenon of Four-Wave Mixing is reduced via the increase of channel spacing. Two multiplexing methods are applied, ultra–wide space division multiplexing (UW–SDM) and ultra–wide wavelength division multiplexing (UW–WDM), where 4000 channels are processed to handle the product of bit rate and repeater spacing for cables of multi-links (50-200 links/core). Two transmission techniques are investigated; namely soliton and maximum time division multiplexing (MTDM). The product per channel is treated over wide ranges of the affecting parameters. The worst real case of power budget and the total time spreading (Four Times Formula FTF) due to the effect of transmitter, optical link, and receiver are deeply investigated over wide ranges of affecting parameters. Dispersion is deeply studied to handle average worst bit rate over the wavelength range (1.45 μm-1.65 μm). This is done through two bandwidths, the worst bandwidth and the normal one. The processing of the worst case clarifies the impact of both the modal dispersion as well as the chromatic dispersion besides the pulse rise time and the receiver rise time. In general, the worst bandwidth BW_w (real case) is less than the ordinary bandwidth (ideal case) BW_c and consequently the worst transmitted bit rate (real case) is less than the ordinary bit rate (ideal case). Both the processed bandwidths {BW_w, and BW_c} decrease as relative refractive index difference (Dn) increases, the operating wavelength increases, and number of links decreases.