Low Phase Noise Direct-Modulation Optoelectronic Oscillator

A direct-modulation OEO (DM-OEO) generating stable 10 GHz and 20 GHz signals is presented. A single loop and a dual loop approach are implemented and compared. We show an output signal of 15 dBm RF power, and a phase noise as low as -135 dBc/Hz at 10 kHz offset from the 10 GHz carrier. The 20 GHz second harmonic exhibits a noise level of -127 dBc/Hz at 10 kHz. A high spur level reduction is also obtained in the dual loop architecture.