Photonic–electronic hybrid microwave source with broadband coverage and ultra-low phase noise

We present a compact optoelectronic microwave source achieving broadband coverage from 1 to 100 GHz with frequency-independent, ultralow phase noise. The system integrates thin‑film lithium niobate modulation with stimulated Brillouin scattering and common mode noise rejection in a high‑Q fiber resonator, enabling a 100 GHz carrier to reach the phase noise level of −111.4 dBc/Hz at 1 kHz and −130.6 dBc/Hz at 10 kHz offset. Then, a 10 GHz signal generated through electrical frequency division and injection locking of a dielectric oscillator is demonstrated, reaching phase noise levels of −84 dBc/Hz at 10 Hz, −124 dBc/Hz at 1 kHz, −138 dBc/Hz at 10 kHz, and −166.43 dBc/Hz at 10 MHz, limited by the noise floor of the synthesizer chip. This architecture overcomes the conventional trade-off between phase noise and carrier frequency, providing a promising solution for advanced communications, radar, and quantum measurements.