Dual-frequency distributed feedback laser with optical frequency locked loop for stable microwave signal generation

We demonstrate the photonic generation of microwave signals by using a dual-frequency distributed feedback waveguide laser in ytterbium-doped aluminum oxide (Al2O3:Yb3+). An optical frequency locked loop (OFLL) was implemented to stabilize the center frequency of the microwave signal. This approach resulted in a microwave frequency at ∼14 GHz with a phase noise of −75 dBc/Hz at 1 MHz offset from the center frequency. The frequency stability of the photonic microwave signal has an Allan deviation of more than 1×10−10 for an averaging time of 1000 s. The combination of the dualfrequency laser and the OFLL scheme holds great potential for the photonic generation and distribution of highly stable microwave or millimeter-wave signals