Potential terahertz radiation by mode conversion from two-color laser to surface plasma waves

A potential terahertz (THz) radiation source generated by mode conversion from laser to surface plasma waves (SPWs) is proposed. The radiation is produced by a two-color laser interaction with a grating. It is shown that the frequency of the THz radiation can be precisely controlled by the frequency difference of the two-color laser. Two-dimensional (2D) particle-in-cell (PIC) simulations are used to verify this mechanism and the results show that the amplitude of the THz electric field increases nonlinearly with the amplitude of the laser electric field, which theoretically means, before the mechanism fails, the intensity of the radiated THz radiation may reach to a pretty high level as long as the driven laser is intense enough. For our simulations, the intensity of the THz radiation is even more than 10% of the laser. Besides, further analysis shows this mechanism also can be used to generate electromagnetic radiation with many other required frequencies by modifying the period of the grating.