理论研究垂直腔半导体光放大器脉冲放大特性

Theoretical study on pulse amplification characteristics of vertical cavity semiconductor optical amplifiers

从速率方程和薄膜光学理论出发,对垂直腔半导体光放大器(Vertical Cavity Semiconductor Optical Amplifiers,简称VCSOAs)在脉冲工作情况下的动态增益进行了数值模拟。在计算中考虑了载流子和光强沿光轴方向的不均匀性,以及腔内介质折射率的不连续性对光波传输的影响。详细分析了反射模式下VCSOA在脉冲通过时载流子密度和瞬时增益的变化、输出光脉冲的畸变以及抽运光功率、分布布拉格反射镜(Distributed Bragger Reflector,简称DBR)周期数、输入脉冲能量以及脉冲宽度等参量对脉冲放大中的能量增益的影响。结果表明,能量增益随抽运光功率增大而增加;在峰值功率一定时输入脉冲宽度的增加将减小能量增益;输入脉冲能量的增加也会引起能量增益的下降,而适当减少顶部DBR的周期数可以改善这种脉冲放大的能量增益饱和特性。

Based on the rate equation and the theory of thin film optics, the dynamic gain of Vertical Cavity Semiconductor Optical Amplifiers（VCSOA） in pulse operation condition was numerically simulated. The longitudinal ununiformities of the carrier density and the optical intensity as well as the discontinuity of the refractive index inside the resonant cavity on the transmission of optical wave were taken into account in the calculation. The evolution process of the carder density in the quantum wells and the temporal gain, the aberration of the output optical pulse were described. The influences of the pump optical power, the distributed Bragger reflector （DBR） periods, the input pulse energy as well as the pulse width on the energy gain during pulse amplification process of VCSOA in reflection mode were analyzed in detail. The result shows that the energy gain increases with the enhancement of the pump optical power and decreases with the broadening of the input pulse width with fixed peak power. The enlargement of the input pulse energy also diminishes energy gain. However, this saturation characteristic of energy gain in pulse amplification can be improved by lowering the top DBR periods.