Effect of laser shape and plasma density on THz Generation

摘要

The development of new and improved terahertz (THz) sources and detectors has become an important research area due to its diverse applications in material characterization, imaging, topography and remote sensing [1], chemical and security identification [2,3], etc. Several schemes, like tunable THz generation by superluminous laser pulse interaction with large band gap semiconductors and electro-optic crystals viz. ZnSe, ZnTe, GaSe, GaP and LiNbO3 have been proposed [4,5]. The other route for THz radiation generation is the laser and plasma interaction [6, 7]. We talk about the THz radiation generation using plasma as a medium, and propose THz generation by photomixing of two laser beams with different spatial field profiles (shapes) in rippled density plasma in the presence of DC magnetic field. Our calculations reveal that more collimated and higher electric field THz radiation can be achieved at a desired position if the lasers with special field profiles are employed. The magnitude of THz field can be further enhanced with large amplitude and narrow ripples in the plasma density.