High THz field emission driven by ionization-induced ponderomotive motions in relativistic plasmas created by CO2 lasers

Terahertz generation by ultra-intense CO2 (10.6 μm) laser fields is studied using particle-in-cell simulations. Photoionization is shown to catastrophically enhance relativistic plasma wakefields, causing a net downshift in the optical spectrum through stimulated Raman scattering.