Slow electromagnetic pulse propagation through a narrow transmission band in a coaxial photonic crystal

Abstract

We demonstrate the slow group-velocity propagation of electromagnetic pulses through a narrow transmission band of a simple coaxial photonic crystal. The narrow transmission band was formed by creating a defect in a periodic coaxial cable filter which resulted in a narrow-frequency passband within an otherwise forbidden band stop region. Strong normal dispersion within this region causes the group velocity of the pulse to be slowed well below the speed of light and below the expected propagation speed in a coaxial cable. This phenomenon is essentially similar to the much-studied slow light propagation observed in atomic vapors through regions of strong dispersion. The simplicity with which this phenomenon can be observed in a one-dimensional coaxial photonic crystal makes this a versatile experiment for such studies. Group velocities of 0.30c, where c is the speed of light in a vacuum, were observed.