Spectral properties of a semiconductor α-DFB laser cavity

The experimental and theoretical investigations of spectral properties of a semiconductor α-DFB laser cavity are carried out. It is shown that in these lasers the curvature of mode gain spectra near the maximum is higher by more than two orders of magnitude than in conventional semiconductor lasers with a Fabry–Perot cavity. The distance between the adjacent axial modes of an α-DFB laser is shorter than in the case of a Fabry–Perot cavity laser of the same length, and its experimental value agrees well with the value obtained in the simple geometrical model, taking into account a zigzag propagation of radiation inside the cavity.