Static, spectral and linewidth measurements of 1.3 µm-range vertical-cavity surface-emitting lasers based on InGaAs/InAlGaAs superlattice are presented. Minimum emission linewidth about 40-45 MHz was obtained at output power of ~3.3 mW and operating current of ~8 mA using the Fabry-Perot interferometer method. During a further increase in the output optical power the emission linewidth broadening could be observed due to the rise of a laser internal temperature (self-heating). Based on the analysis of the internal optical losses and internal quantum efficiency the linewidth enhancement factor (α-factor) was evaluated at about 7.7‒9 depending on population inversion factor of 2-1.5.