Phase Noise of Optically Generated Microwave Using Sideband Injection Locking

Optically generated 20-GHz microwave carriers with phase noise lower than -75dBc/Hz at 10kHz offset and lower than -90dBc/Hz at 100kHz offset are
obtained using single- and double-sideband injection locking. Within the locking range, the effect of sideband injection locking can be regarded as narrow-band amplification of the modulation sidebands. Increasing the current of slave laser will increase the power of beat signal and reduce the phase noise to a certain extent. Double-sideband injection locking can increase the power of the generated microwave carrier while keeping the phase noise at a low level. It is also revealed that partially destruction of coherence between the two beating lights in the course of sideband injection locking would impair the phase noise performance.