Low-Noise X-Band Tunable Microwave Generator Based on a Semiconductor Laser With Feedback

The stabilization of a relatively simple microwave oscillator tunable across the full X-band based on a laser subjected to optical feedback is achieved. Specifically, a resonance effect based on locking the two inherent dynamic frequencies of the system, as well as, optoelectronic feedback are utilized to achieve a sub-ps jitter and typical phase noise in the range of -107 dBc/Hz at 10 kHz offset from an oscillation frequency that can be tuned from 5.5 to 12.1 GHz. Further, the microwave signal is extracted from the laser-diode injection terminals and eliminates the need for multiple lasers, radio-frequency filters, and external RF sources. This architecture, therefore, realizes a compact and low-cost tunable microwave photonic oscillator.