Concentration and effective temperature of carriers are established to compete in their influences on the band‐edge dielectric function of an active semiconductor medium under the lasing conditions. This competition is shown as capable of suppressing the relaxation oscillations and wavelength chirping in the modulation response of a semiconductor laser, provided the carrier injection and carrier heating are combined in a suitable way. The problem of how to combine them is studied under the small‐signal approximation assuming that modulation signal can be imposed on both the injection current and energy flux flowing into the active layer. All the numerical results relate to single‐frequency 1.55 &mgr;m GaInAsP/InP laser. ©1995 American Institute of Physics.