Modified Drude model for free-carrier absorption due to bound-to-continuum transition in quantum-dot semiconductor optical amplifier

作者：Li, Xiaoming; Wang, Tao^*; Dong, Chuanbo; Tang, Jian; Liu, Bo; He, Yu

来源：Journal of Applied Physics, 2013, 114(15): 154506.

DOI：10.1063/1.4825255

• CROSS-GAIN MODULATION
• PHASE

Within the framework of the second-order perturbation theory, a model is presented to calculate the cross-section of the free-carrier absorption (FCA) due to phonon-assisted bound-to-continuum transition in quantum-dot semiconductor optical amplifier (QD-SOA). It is shown that the cross-section of the FCA in QD layer is much larger than that in bulk system when the photon energy is in the vicinity of the carrier binding energy. Conversely, when the photon energy is very large, the coefficients of the FCA for QD system and bulk system are on the same level of magnitude. And these conclusions agree well with the classical theoretical model and experimental results reported previously. In order to develop a simple and exact model to predict the FCA due to bound-to-continuum transition, a modified Drude model is proposed. The modified model contains the carrier's confinement energy between the quantum dot layer and the barrier layer. The results show that the absorption cross-section calculated from first principles is given asymptotically by the modified Drude model at room temperature, especially when the binding energy is very large.

• 出版日期2013-10-21
• 单位华中科技大学