Reconfigurable multi-tone mmWave/THz generation powered by high-efficiency Kerr parametric oscillation

Abstract

Broadband and simultaneously accessible multi-tone millimeter-wave (mmWave) and terahertz (THz) signals are attractive for multi-band wireless communication and spectroscopy applications, yet their generation remains constrained by electronic bandwidth limitations and inefficient optical frequency conversion. Here, we demonstrate reconfigurable photonic generation of multi-tone mmWave/THz signals with comb spacings of 100, 200, 300, and 400 GHz, using a strongly asymmetric dual-ring silicon-nitride (SiN) microresonator and a broadband spiral plasmonic photomixer. A localized avoided-mode crossing (AMX) introduced by an auxiliary ring supports a fixed optical parametric oscillation (OPO) mode pair over an extended pump-detuning range, consistent with passive compensation of detuning-dependent phase mismatch. This enables a maximum pump-to-generated-line conversion efficiency of 67.3 % with 25.06 dB of pump depletion across different pump wavelength selections. Direct photomixing of these optical states produces simultaneous multi-frequency tones spanning 100 to 900 GHz without intermediate optical amplification. The generated carriers are further characterized through down-converted spectra, frequency-noise power spectral density (PSD), and Allan deviation measurements, yielding a \b{eta}-separation linewidth of 26 kHz at an observation time of 0.1 s. Optical modulation offers high radiated power levels exceeding 2 mW at 100 GHz at a duty cycle of 1 %, while mitigating thermal breakdown in the photomixer. High optical conversion efficiency, reconfigurable and selectable comb spacings, and broadband multi-tone generation on a chip-scale platform provide a compact route toward reconfigurable multi-band mmWave/THz sources for wireless communication, spectroscopy, and sensing.