量子点半导体光放大器的自发辐射特性研究

ASE of quantum dots semiconductor optical amplifiers

从导带、价带和浸润层的能级跃迁出发,采用分段模型对量子点半导体光放大器的增益和自发辐射进行了数值研究.物理模型包括自发辐射行波方程和各能级载流子与光子数速率方程.经过大量数值计算,得到基态电子占用概率随注入光脉冲的变化,以及增益动态过程(饱和与恢复)和输出光脉冲的时域波形畸变.进一步研究了量子点光放大器自发辐射谱和增益平坦性,结果表明自发辐射功率随输入信号功率增大而减小,引入合适的钳制光,可在20 nm带宽内获得小于0.3 dB的增益平坦度,或者40 nm带宽内小于1.0dB.

Based on the energy level transitions in the conduction band, the valence band, and the wetting layers, the spontaneous emission process and the gain dynamics in the quantum dots semiconductor optical amplifier （QD-SOA） is investigated by a numerical model, which includes a series of traveling-wave equations for the spontaneous emission, and a series of rate equations for the carriers and photons. The amplifier is split into a number of sections for the simulations of the carriers and photons evolution along the propagation distance in the QD-SOA. The dependence of the electron occupation probability of the ground state on the input optical pulse, hence the gain dynamics （saturation and recovery） and the distortion of the output optical pulse, are obtained with plenty of computations. The amplified spontaneous emission spectra and the gain flatness of the QD-SOA are simulated, and the results show that the ASE decreases with the input optical power, and the gain flatness will be less than 0.3 dB in a band of about 20 nm, or 1.0 dB in 40 nm.