Nanoantennas streamline photomixing terahertz source capabilities

A team at A*STAR (Singapore) and Imperial College London (London, England) incorporated nanoantenna structures into a photomixer and found that emission power could be enhanced by more than two orders of magnitude compared to a terahertz photomixer using typical interdigitated electrodes. This new nanoantenna-incorporated photomixer could be an enabling technology toward highly efficient, compact CW terahertz sources for high-resolution imaging and spectroscopy systems. In the photomixing experimental setup, two tunable lasers with specific terahertz offset frequencies were used as an optical pump. The measured CW terahertz emission of the photomixer with interdigitated electrodes and tip-to-tip nanogap electrodes showed significant enhancement in the output power across a bandwidth of approximately 1.3 THz. COMSOL Multiphysics simulation software from COMSOL, Stockholm, Sweden, showed that the capacitance of the tip-to-tip nanogap electrodes is more than one-third smaller than the capacitance of the interdigitated electrodes.