This dataset contains the data points of all figures on the paper "Quasi-Single-Mode Transmission over Ultra-Low-Loss Few-Mode Fibre for Data Centre Interconnects". A description of the files is presented below:nli_ase_fitting.xlsx, snr_vs_lpower_fitting.xlsx & snr_vs_lpower_fibrea_ullfmf.xlsx: These files contain the signal-to-noise ratio as a function of launch power for the full reproduction of Fig. 2(a).snr_vs_fde.xlsx & snr_vs_tde.xlsx: These files contain, respectively, the signal-to-noise ratio as a function of the channel impulse response length and the number of filter taps for fibre A and the ultra-low-loss few-mode fibre. The file filter_taps.xlsx allows analysing the filter weights obtained with the radius directed equaliser for the ultra-low-loss few-mode fibre. They allow full reproduction of Fig. 2(b).mpi_vs_wav.xlsx: This file contains the multipath interference results as a function of the wavelength obtained based on power samples and on the modified Gaussian model. It allows full reproduction of Fig. 3.snr_vs_wav.xlsx: This file contains the signal-to-noise ratio analysis as a function of the wavelength for fibre A and the ultra-low-loss few-mode fibre. Results were obtained with and without digital backpropagation. This file allows full reproduction of Fig. 4.