The tuning of the laser is done in such a way that the DAC value (be it in % or DAC) is different for every laser. The % value is simply the % of rail voltage (3.3 V). You can change the [%] value in the settings file. The width of the pulse is related to DAC value. The driver current pulse is limited by the threshold (only the fraction above threshold is led through) that is why both are related. However, up to 10% from the peak value the width is roughly constant of FWHM~350 ps (this is the place where it is mostly used). After that it gets wider and reaches maximum width of 4 ns at DAC = few %.