Terahertz wave generation from crossing air-plasmas

Air-plasma is a convenient method to generate intense terahertz (THz) waves by focusing the dual-color laser pulse on air molecules. Generally, the plasma property is associating to the intensity and frequency of the generated THz waves. Here, we demonstrated the varying intensity of THz wave generation from two crossing-beams of the dual-color laser-induced air-plasmas. When the two crossing beams overlap spatially and temporally, the structure and luminance of the combined plasmas changed greatly. In addition, the generated THz waves is not a simple coherent superposition of the two terahertz waves, but the spatial emission property and the maximum output angle is redistributed and redirected. Our results can help to gain more insight on the mechanism of THz wave generation from air-plasma, and offer a new possible modulation method for THz wave generation via controlling the spatial structure and complex dynamics inside the air-plasmas.