高斯波包在截止波导中的传播

Anomalous Propagation of Gaussian Wave Packet Through the Cut-Off Waveguide

分析了电磁波传播时的超光速群速。对高斯波包在分段填充不同介质的波导中的传播情况进行了数值模拟,得到高斯波包通过截止区的群速和能速,并对其中涉及到的“超光速”问题作了一定的分析。通过模拟得出,在一定的截止区长度范围内和一定工作频率范围内,群速超过光速;并得到,波包的能量传播速度(能速)始终不会超过光速。

A simple analysis is made of the superluminal group velocity. The anomalous propagation of an electromagnetic Gaussian pulse through a waveguide with piecewise different dielectric constants is simulated. At the same time, the group velocity and energy velocity of Gaussian wave packet through cutoff region are calculated. And, the ＂superluminar＇ problem is analyzed involved in it. From the result of simulating, it is gained that when the length of cutoff region and the work frequency are in one range, group velocity is greater than the light speed in vacuum. But energy velocity is smaller than the light speed in vacuum all long.