We study the propagation of light pulses in an absorbing medium when the frequency of their carrier coincides with a zero of the refractive index dispersion. Although slow light and, a fortiori, fast light are not expected in such conditions, we show that both can be obtained by selecting particular phase components of the transmitted field. Analytical expressions of the resulting signals are obtained by a procedure of periodic continuation of the incident pulse, and a proof of principle of the predicted phenomena is performed by means of a very simple electrical network; the transfer function of which mimics that of the medium.

中文翻译：

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零色散配置中的慢速和快光

我们研究了当光脉冲的载波频率与折射率色散为零时在吸收介质中的传播。虽然速度慢光，更不用说，快速光预计不会在这样的条件下，我们表明，两者都可以通过选择所发送的字段的特定相位分量而获得。所得信号的解析表达式是通过入射脉冲的周期性连续过程获得的，而预测现象的原理证明是通过非常简单的电网进行的；传递函数模仿介质的传递函数。