Electronic-Spintronic Terahertz Emitter

We present a terahertz (THz) radiation source combining the principles of spintronics and vacuum electronics: the electronic-spintronic THz emitter (E-STE). Different from the traditional laser-driven spintronic THz emitters, E-STE is driven by low-energy electron beams. Working through four steps: the electron-beam excitation of hot electrons, the electron superdiffusion, the inverse spin Hall effect, and the diffraction radiation of the periodic gratings, E-STE is able to emit continuous, monochromatic THz radiation. Detailed theoretical modeling and numerical calculation show that E-STE can cover the whole THz-frequency regime (0.1-10 THz) by modifying the period of the gratings. The electron beam voltage and current are relatively low (voltage U=5 V, 25 V, peak current I similar to 100 mA), while the radiation power density and working efficiency are relatively high. (The power density can reach 10(8) W/cm(2), the working efficiency can reach 25%.) This compact and high-power E-STE may contribute to the development of a THz-radiation source integrated on chip.