Ponderomotive force induced nonlinear interaction between powerful terahertz waves and plasmas

We have investigated the ponderomotive force induced nonlinear interaction between terahertz (THz) wave and plasmas. The effects of ponderomotive force on the THz beam-width and spatial electric intensity distribution are investigated in different incident THz wave frequencies. It is observed that ponderomotive force can make THz beam focusing, and the higher the THz wave frequency, the more stable the focusing effect will be. The characteristics of THz beam will also be affected by plasma density. This unique nonlinear interaction may be exploited in novel THz driven optical modulators and switches.