Characterization of narrowband 100 GHz signals generated by a spectrally interleaved microcomb source

We report generation and characterization of narrowband 100 GHz signals via a uni-travelling-carrier photodiode (UTC-PD) pumped by a spectrally interleaved mode-locked microcomb source. The output frequency was characterized by directly detecting the optical beat signals with a fast photodiode and then mixing with a multiplied local oscillator (LO) in an electrical spectral analyzer (ESA). The 3 dB bandwidth below 10kHz was observed without any feedback control even when pumped by multiple lines of combs. Our results highlight future possibilities of stable and compact millimeter-wave / terahertz signal sources with low power consumption.