Gain saturation in InP∕GaInP quantum-dot lasers

Abstract

We have measured the gain-current and gain-quasi–Fermi level separation characteristics for InP∕AlGaInP quantum-dot-laser structures. Saturation of the gain-current characteristics is apparent even though photoluminescence excitation spectroscopy measurements indicate that the 2D states are energetically distant from the dot states. The gain is reduced from the maximum value by the distribution of carriers in the excited dot states, the states in smaller dots and the 2D states.