混沌信号在光纤传输过程中的非线性演化

Nonlinear evolution of chaotic signal transmission in optical fiber

对光纤混沌传输理论及混沌信号与光纤传输媒介相互作用的物理机制进行了理论研究.通过耦合激光混沌系统和光纤传输信道,提出光纤混沌信号传输的非线性演化物理模型.着重分析光纤自相位调制对激光混沌信号传输与演化的作用.结果表明:自相位调制不影响混沌信号脉冲的形状,但能产生非线性相移使混沌信号频谱展宽;自相位调制不影响混沌信号脉冲的功率分布和场强分布,但能影响混沌信号脉冲的功率频谱分布,影响混沌信号光场以及慢变场的变化.提出混沌信号在光纤传输中的非线性演化频率啁啾和形式,数值模拟了混沌信号在光纤传输过程中的相位、频谱、场以及场的慢变部分的相空间等演化形式和特点.

Theory of chaotic signal transmission in optical fiber and physical mechanism of chaotic signal acting on optical fiber transmission medium are theoretically studied. A physical model of nonlinear evolution of chaotic signal propagation in optical fiber is presented by coupling chaotic laser system with optical fiber channel. Action of self-phase modulation of optical fiber on propagation and evolution of chaotic signal is analyzed in detail. Self-phase modulation of fiber does not affect the pulse shape of chaotic signal, however, its product of nonlinear phase shift can widen the chaotic signal spectrum. Self-phase modulation does not affect the power distribution and field intensity distribution of chaotic pulse signal. However, it can affect the power spectrum distribution, the transformation of optical field of chaotic signal and field＇ s slow-variying part. A frequency chipped model of nonlinear evolution of chaotic signal in fiber is presented. The evolution and characteristic of the phase, spectrum, field and field＇s slow-varying part in fiber are numerically simulated.