Intrinsic instabilities in narrow stripe geometry lasers caused by lateral current spreading

Lateral current spreading in an otherwise perfectly homogeneous narrow stripe geometry laser causes spontaneous oscillations when the device is operating at the appropriate current level. Such intrinsic instabilities are also influenced by diffusion and by the transverse variation of the carrier lifetime. In this paper, the above intrinsic mechanism is discussed on the basis of a simple model consisting of an active slab waveguide with time varying parameters and upon application of a stability analysis.