Temperature dependence of gain saturation in multilevel quantum dot lasers

The temperature dependence of quantum dot (QD) optical gain is analyzed usi ng a multilevel model and compared with experiment. The maximum gain is fou nd to have a surprisingly strong temperature dependence that causes level s witching and can limit laser performance in QD lasers. The model based on m ultiple discrete levels elucidates general design criteria that should be s atisfied to obtain a stable threshold versus temperature in QD lasers. Good agreement is obtained between calculations and experiment for level switch ing in 1.3-mu m QD lasers.