  We have investigated modulation instability in metamaterials (MM) with both
cubic and quintic nonlinearities, based on a model appropriate for pulse
propagation in MMs with cubic-quintic nonlinearities and higher order
dispersive effects. We have included loss into account in our analysis and
found that loss distorts the sidebands of the MI gain spectrum. We find that
the combined effect of cubic-quintic nonlinearity increases the MI gain. The
role of higher order nonlinear dispersive effects on MI has been also
discussed.
