  We study the group velocity of light in layer-by-layer chiral photonic
crystals composed of dielectrics and metals. Through studying the band
structures with an extended-zone scheme that is given by a Fourier analysis, we
show the existence of negative group velocity in the proposed chiral
structures. The physical mechanism is interpreted with the help of a simplified
model that has an analytical solution. The iso-frequency contours of the
photonic band structure suggest that the negative group velocity can lead to
either positive or negative refraction, depending on the orientation of the
medium interface. We propose a feasible realization of such kind of photonic
crystals. Computational results on the proposed realization are consistent with
that of the simplified models.
