基于Volterra级数分析的半导体激光器非线性模型

Nonlinear model of semiconductor laser diodes based on Volterra series analysis

根据非线性系统Volterra级数分析理论建立了半导体激光器的非线性模型.半导体激光器由本征激光器与寄生网络级联而成.本征激光器的非线性传递函数利用谐波输入法从速率方程得到,而寄生网络的非线性传递函数由影响其非线性的主要因素决定.在此基础上利用非线性系统的级联关系得到半导体激光器的非线性传递函数,并利用模型计算了半导体激光器的二次谐波、三次谐波和三阶交调失真.计算结果显示,在宽频范围内模型计算结果与仿真结果接近,且寄生网络对于激光器非线性的影响随频率升高而逐渐加大.通过比较Volterra模型与直接仿真之间的误差随输入信号功率的变化趋势可看出Volterra模型更加适用于分析弱非线性系统.所建立的模型有助于半导体激光器的器件表征与射频光传输系统的设计.

A nonlinear model for semiconductor lasers is presented based on the Volterra series analysis of nonlinear systems.The semiconductor lasers are composed of the cascaded network of intrinsic laser and parasitic network.The nonlinear transfer functions of the intrinsic laser are derived from the rate equations by the harmonic input method.The nonlinear transfer functions of the parasitic network are acquired by taking into account the main factors that affect the nonlinear behavior in parasitic network for the specific application.Then the total nonlinear transfer function is derived by using the cascading relationship of the nonlinear systems.The second-and third-order harmonic distortion and the third-order inter-modulation distortion are calculated and simulated.The comparison between the analysis and simulation results shows that they are matched closely in a wide frequency range.The influence of the parasitic network on the nonlinearity of the laser increases gradually with the increase of the frequency.The comparison of the error between the Volterra model and the simulation results with different input powers shows that the Volterra model is more suitable for the analysis of the weak nonlinear system.The model is useful for the device characterization and the design of radio-over-fiber（ROF） systems.