Spectral stability analysis of weakly coupled external-cavity semiconductor lasers

Abstract

The spectral stability of weakly coupled external-cavity semiconductor lasers is studied theoretically. The carrier density modulation induced at the frequency of the external-cavity mode spacing f ex plays an important role in the spectral instability. Therefore, the laser under optical feedback reveals different spectral behaviors, depending on the relation between the frequency of the external-cavity mode spacing and the relaxation resonance frequency f R of the carrier density. For a better spectral stability, f ex must be larger than f R .