High-power vacuum terahertz photomixer and integrated circuits based on microscale phototubes

Technologies and industrials in long-distance communication, detection, and imaging applications are still in great need of higher-output-power terahertz sources. This paper proposes two kinds of microscale vacuum phototube based high-power terahertz source: vacuum photomixer and terahertz integrated circuit. The principle of photomixer based on photoemission and field-assisted photoemission is demonstrated. Its capability of producing radiation power beyond 1 mW is estimated based on theoretical analysis and experimental evidence. Simulation and theoretical analysis have shown that the fundamental THz photodiode devices can operate with a space-charge limited current density of 4496 A/cm² at 60 V, and the amplifier circuits are calculated to have a gain performance of around 10 dB. The two photoemission-based roadmaps have the potential to be developed from an emerging and interdisciplinary field to more promising future directions of THz science and technology.