Characterization of the chirp in semiconductor laser under modulation

In this paper we present, shortly, a study of the chirp induced in direct modulated DFB laser. Our description of the chirp is based, first on analytical resolution of the rate equations, and second on a simulation of a heterodyne system with the Optisystem software. This study enables us to visualize the chirp of a DFB laser in the RF field and to characterize it according to the parameters of the modulation of the injection current i(t). We show by using the powerful Volterra series theory that the linear sweep of the laser optical frequency can be obtained by a triangular modulation of the injection current.