Spectral studies of electroluminescence have been conducted on edge-emitting lasers with different cavity lengths. Mirrors were formed by focused ion beam technique and cleaving. A wide range of injection currents was used. Active region of the lasers consists of dense arrays of InGaAs/GaAs quantum dots, which enabled to obtain lasing in stripe lasers with cavities as short as 45 µ m. A noticeable blueshift of the lasing wavelength was observed with the cavity length decrease, accompanied by an increase in the threshold current density. The maximum modal gain was estimated to be at least 267 cm-1.