Two-Color Terahertz Radiation Emission in Quasi-Periodic Smith–Purcell Structures

We study the Smith-Purcell (SP) radiation emission generated in terahertz (THz) frequency range by an electron beam passing close to the surface of a 3-D quasi-periodic array of metallic slots. When more than one electron beam is used in the SP-based periodic structures, the two or more colors can be generated. In this paper, two-color SP emission of radiation with variable frequency separations has been examined in a proposed quasi-periodic Fibonacci-class structure through 3-D-particle-in-cell (PIC) simulations. In spite of using an electron beam instead of implementing a double-electron beam streaming method, in this paper, a new method for successful two-color SP radiation generation in the THz frequency domain is reported in both quasi-spontaneous and quasi-super-radiant regimes. Finally, we show that quasi-superradiance simulations demonstrate the possibility of frequency separation controlling through repetition frequency of applied periodic bunches.