A frequency-tunable photonic terahertz oscillator referencing to a microresonator frequency comb

A microresonator frequency comb (microcomb) allows us to make a compact photonic millimeter- and terahertzwave oscillator with ultra-low phase noise. However, it lacks frequency tunability owing to the fixed resonator size. In this study, we develop a low-noise terahertz-wave oscillator tunable over a wide frequency range by employing two continuous-wave lasers phase-locked to a microcomb. We perform an output frequency sweep over more than 300 MHz at a center frequency of around 300 GHz. In addition, we show that the tuning range can be extended to be more than 10 GHz.