  We propose a compound system consisting of a dielectric grating and a
plasmonic resonance cavity embedded in the grating. Based on the interference
effect between the surface mode supported by the dielectric grating and the
plasmonic-induced cavity mode, this system could achieve slow light with group
index more than 200 and transmission more than 75%. Meanwhile, we examine the
effects of the period numbers of the compound system and photonic crystal
superlattice made up of alternate layers of the grating and air on the
properties of slow light.
