Read me file: University of Southampton – ORC – Huaiqin Lin – hl3g15@soton.ac.uk The excel file contains experimental data for the paper. In particular: Fig. 2(a). Laser output power versus launched pump power. Fig. 2(b). laser output spectrum at 405 W output with a resolution of 1 nm. Fig. 3(a). High-intensity irregular-frequency self-pulses from the Er-doped fiber laser at an output power of 200 W. Fig. 3(b). One transient oscillation of the self-pulses. Fig. 3(b) inset. The temporal trace of an individual self-pulse. Date of data collection: from February 2017 - May 2017 Information about geographic location of data collection: University of Southampton, U.K. Date that the file was created: August 2017