A 170–260-GHz high-power tripler using a large-scale SPP-resonant diode array

This Letter presents a 170–260-GHz tripler featuring a novel 16-element square-ring Schottky-diode array tailored for surface-plasmon polariton (SPP) resonance. To overcome severe field nonuniformity issues inherent in large-scale multi-diode arrays, both the transverse and longitudinal chain lengths of the square ring are designed according to the SPP half-wavelength (≈161–246 μm) calculated from the dispersion relation. This configuration transforms parasitic traveling waves into a stable standing-wave resonance within the closed-loop cavity, simultaneously achieving uniform electromagnetic excitation and thermal distribution among all 16 diodes—a key factor in maximizing power-handling capability. Measured results at room temperature show a conversion efficiency of 4%–8% across the full 170–260 GHz band. Notably, the device combines a low-drive power requirement (<30 mW) with a high-power-handling capacity (>450 mW), delivering a peak output of 17 mW at 205 GHz. This work validates the SPP-resonant concept as a critical design methodology for frequency-extension stages.