An analytical solution of kinks and nonlinearities driven by near‐field displacement instabilities in stripe geometry diode lasers

摘要

An analytical expression which describes the lateral shift of the lasing mode in a diode laser as an implicit function of injection current is derived for stripe geometry lasers, without numerically evaluating the full self‐consistent carrier and field equations. If the onset of the lateral mode shift is associated with a kink in the optical power‐current characteristic, then the predicted kink power as a function of stripe width agrees quite well with experiment. Self‐focusing of the near field is predicted to occur for wider stripe lasers, in general agreement with observation. The effect of the strain‐induced dielectric profile on the kink power is calculated and found to be minimal for oxide isolated lasers of practical active layer depth. The parameters which profoundly affect the kink power are stripe width, carrier diffusion length, and near‐field width.