Superluminal pulse reflection from a weakly absorbing dielectric slab
  Group delay for a reflected light pulse from a weakly absorbing dielectric slab is theoretically investigated, and large negative group delay is found for weak absorption near a resonance of the slab ($Re(kd)=m\pi$). The group delays for both the reflected and transmitted pulses will be saturated with the increase of the absorption. 
Li-Gang Wang and Shi-Yao Zhu