A novel terahertz plasma-wave photomixer with resonant-cavity enhanced structure

Two-dimensional (2D) plasmon in a submicron transistor channel can make resonant oscillation in the terahertz range. We propose a novel terahertz plasma-wave photomixer that can improve the conversion gain and terahertz radiation power. The photomixer is based on a high-electron mobility transistor (HEMT) and incorporates doubly interdigitated grating strips for the gate electrodes that periodically localize the 2D plasmons in sub 100-nm regions with a micron-order interval. A vertical cavity structure is formed in between the top metal grating and a terahertz mirror placed at the backside. FDTD simulation demonstrates that a newly-introduced vertical cavity structure effectively enhances the conversion gain and radiation power.