有源光纤自相位调制的频谱展宽估计

有源光纤的两种非性效应－非线性极化和增益饱和效应都引起光信号频谱展宽。增益饱和导致包络失真，同时也影响到由非线性极化所造成的自相位调制。这种影响可用一个函数ｆ（ｚ）表示。

Estimation of Frequency Spectrum Broadening Caused by Self Phase Modulation in Active Fiber

In active fiber two kinds of nonlinearity, nonlinear polarization and gain saturation, laed to the frequency spectrum broadening of optical signal. Gain saturation distorts its envelope, and affects the self-phase-modulation (SPM) caused by nonlinear polarization. It can be expressed by a transmission function f(z). A formula of f(z) with a power series derived from NLS equation is given, and the frequency broad band can be estimated by B=2F(1+μ). Because of f(z)>>1 in the active fiber, the broadening can be compared with initial band of optical signal in the optical communication system having many optical fiber amplifiers with high gain and high output power.