Tunneling time of an optical pulse in a photonic bandgap

Tunneling time (or group delay) for an optical pulse to transmit the energy through a photonic bandgap is calculated analytically for a one-dimensional multilayered optical superlattice. The analytical solution shows that the calculated tunneling time converges to a finite value with increasing numbers of layers, and we have derived the formula for the converged value of the tunneling time. This effect is similar to the so-called Hartman effect in a quantum system. Because of the destructive interference of multireflected light in the superlattice, the tunneling time is determined by an exponentially decaying evanescent wave, which is the reason for this effect.