Modulations of THz Wave from Vortex Beam Induced Air Plasmas

In this paper, we demonstrate a method to modulate the intensity and central frequency of THz generation from two-color laser-induced air plasmas, via transforming the pump Gaussian beams into vortex beams. Under the same input laser energy, the outputs of THz emission generated by the vortex beam can be enhanced, showing the potential of producing stronger THz radiation. Meanwhile, the vortex pump-beams also provide an unique possibility to modulate the central frequency of THz outputs, implying an all-optical method of THz modulation based on the shaped plasmas.