The modulation response of a semiconductor laser amplifier

We present a theoretical analysis of the modulation response of a semicondu ctor laser amplifier. We find a resonance behavior similar to the well-know n relaxation oscillation resonance found in semiconductor lasers, but of a different physical origin. The role of the waveguide (scattering) loss is i nvestigated in detail and is shown to influence the qualitative behavior of the response, In particular, it is found that a certain amount of waveguid e loss may be beneficial in some cases. Finally, the role of the microwave propagation of the modulation signals is investigated and different feeding schemes are analyzed. The nonlinear transparent waveguide, i.e., an amplif ier saturated to the point where the stimulated emission balances the inter nal losses, is shown to be analytically solvable and is a convenient vehicl e for gaining qualitative understanding of the dynamics of modulated semico nductor optical amplifiers.