定义:
在一定条件下由孤子波分裂而成的线性传播的光波
当光脉冲入射到具有反常色散的光纤中时,脉冲参数并不与孤子完全匹配,脉冲将演变(在光纤内传播一定距离后)成孤子脉冲和一些时域上扩散开来的背景。其中后者被称为色散波,因为它是因群延迟色散的效果而扩散开来的。由于峰值功率太低,导致其不能被光纤非线性补偿。初始脉冲的越接近孤子脉冲的参数,则越多的脉冲能量为存在在孤子中,只有很少的能量会变成色散波。
当孤子传播条件被某种方式打破时,如光纤的局部损耗(导致脉冲能量突然降低,从而偏离孤子传播条件)或者传输到另一个参数略微变化的光纤中。类似的效果也会在准孤子脉冲的锁模激光器中发生,因为其中的色散和非线性通常发生不同的地方,而不是均匀的分布在谐振腔中。循环的孤子因此受到周期性的干扰,使得孤子与色散波同时传播。这也会在锁模光纤激光器中发生,虽然光谐振器由光纤构成,但是由于在每次循环中脉冲能量会经历大的变化,且腔中不同的光纤具有不同的色散或非线性系数。这种周期性扰动的孤子循环可导致凯利边带的形成。
Definition: a linearly propagating wave which is split off by a soliton wave under certain conditions
When a light pulse is launched into a fiber with anomalous chromatic dispersion so that the pulse parameters do not exactly match those of a soliton, the pulse will evolve (within some propagation distance in the fiber) into a soliton pulse and some temporally spreading background. The latter is called a dispersive wave, because it is spreading due to the effect of chromatic dispersion, and this is not compensated by the fiber nonlinearity, since the peak power is too low. The closer the parameters of the initial pulse are to the parameters of a soliton, the higher is the percentage of the pulse energy which ends up in the soliton rather than in the dispersive wave.
A dispersive wave can also be formed when the soliton is disturbed in some way, e.g. by a localized loss in the fiber (causing a deviation from the soliton condition by suddenly reducing the pulse energy) or by the transition into a fiber with modified parameters. Similar effects occur for quasi-soliton pulses circulating in the resonator of a mode-locked laser, where dispersion and nonlinearity usually occur in discrete packages rather than smoothly distributed as in a fiber. The circulating soliton is thus subject to periodically occurring disturbances, which couple the soliton to the copropagating dispersive wave. This also happens in a mode-locked fiber laser, even if its laser resonator is made from fibers only, since the pulse energy usually undergoes large changes in each round trip and also because fibers with different dispersion and/or nonlinearity may be used within the resonator. The periodic disturbance of the circulating soliton can result in the formation of Kelly sidebands.