  We have experimentally demonstrated an ultra-dispersive optical prism made
from coherently driven Rb atomic vapor. The prism possesses spectral angular
dispersion that is six orders of magnitude higher than that of a prism made of
optical glass; it is the highest spectral angular dispersion that has ever been
shown (such angular dispersion allows one to spatially resolve light beams with
different frequencies separated by a few kHz). The prism operates near the
resonant frequency of atomic vapor and its dispersion is optically controlled
by a coherent driving field.
