Transients in injection lasers-phase-plane analysis and effects of absorbing sections

A new phase-plane analysis of transients in injection lasers is presented, which leads to general conditions for no ringing in the light output. For operation not meeting the general conditions, it is shown that a double-step current modulation of the laser can reduce the amplitude of the ringing. The result of this analysis is then applied to a laser with absorbing sections. It is shown that the enhanced superluminescence in these lasers will produce an effective double-step drive when a single-step drive is externally applied. This result then helps to explain why various kinds of lasers with absorbing section show little or no transient photon oscillations.