High efficiency and output power achieved in terahertz emitters

In between microwaves and infrared light, there’s an underutilized gap in the electromagnetic spectrum. This terahertz gap has uses from communications to medical and scientific imaging, but there’s a lack of commercially viable equipment that can function at these wavelengths. The most promising emitters in the terahertz gap are resonant-tunneling diode (RTD) oscillators, but they often do not have sufficient power output.

In an experimental study, Picco et al. built on their prior theoretical work to improve the output power and efficiency of RTD oscillators. Previously, the researchers’ theoretical studies found that thin-barrier RTDs with a high current density could dramatically increase output power. Fabricating, measuring, and analyzing a large set of RTD oscillators, they showed that thin barrier RTD oscillators could indeed reach exceptionally high efficiencies of 11% at around 220 GHz and 8% at around 420 GHz. The experiment also showed the highest reported output powers for simple symmetrical slot-antenna RTD oscillators.

“The results fully confirm those earlier theoretical insights, providing a solid foundation for future design and optimization of RTD oscillators,” said author Michael Feiginov. “The results also provide a valuable design guideline that can support both our future work and that of the wider community in achieving improved oscillator performance.”

That design guideline can be broken down into two simple design principles: Thin barrier, high current density RTDs can reach high output power and efficiency even at relatively low frequencies, and separate designs are needed for maximum efficiency and maximum power output. The researchers are continuing to extend the findings to other types of RTD oscillators.

Source: “Maximizing output power and efficiency in resonant-tunneling-diode oscillators: Role of high current density,” by G. Picco, P. Ourednik, and M. Feiginov, APL Engineering Physics (2026). The article can be accessed at https://doi.org/10.1063/5.0327594 .