Conceptual question: THz generation in ZnTe

[VedranJ]

When a broadband 800nm sub-ps pulse propagates through ZnTe parallel to the {110} plane it produces in-phase THz radiation by moving the electrons down either the [-111] or [1-11] axis.

Due to the electronegativity of Zn and Te the electric field of the optical pulse will push electrons closer to the tellurium than the zinc leading to a DC offset known as optical rectification.

My question is whether the THz gets produced when the pulse first propagates through and moves the electrons up and down (accelerates), or after the pulse passes and the DC offset electrons relax (decelerate) to produce THz radiation.

 

[BigJDubs]

The THz radiation is produced when the pulse propagates through and accelerates the electrons. As the electrons oscillate in response to the electric field of the pulse, they emit radiation in the form of THz waves. After the pulse passes, the DC offset electrons relax to their original positions, but do not produce any additional THz radiation.