  Spectral red-shifting of high power laser pulses propagating through
underdense plasma can be a source of ultrashort mid-infrared (MIR) radiation.
During propagation, a high power laser pulse drives large amplitude plasma
waves, depleting the pulse energy. At the same time, the large amplitude plasma
wave provides a dynamic dielectric response that leads to spectral shifting.
The loss of laser pulse energy and the approximate conservation of laser pulse
action imply that spectral red-shifts accompany the depletion. In this paper,
we investigate, through simulation, the parametric dependence of MIR generation
on pulse energy, initial pulse duration, and plasma density.
