We present theoretical and experimental second- and fourth-order inter
ference patterns for entangled photons of different colors entering si
ngle and dual Mach-Zehnder interferometers in which dispersive element
s have been deliberately placed. Although photon wave packets are gene
rally broadened, as well as delayed, by passage through dispersive opt
ical,elements, coincidence measurements made with entangled photon pai
rs can be free of such broadening. This occurs for materials with part
icular dispersive behavior, as well as when the dispersion is balanced
in both arms. This nonlocal behavior arises from the entanglement in
the frequencies of the down-converted pair photons. We also show that
nonlocal pump-frequency oscillations are present in the coincidence ra
te patterns for long path-length-difference times, confirming the robu
stness of this phenomenon in the presence of dispersion. However, the
magnitude of these oscillations is reduced when an arbitrary dispersiv
e material is used in an unbalanced configuration. Difference-frequenc
y oscillations are also robust in the presence of dispersion, although
they decay for large path-length-difference times.