A Novel Optoelectronic Oscillator Based on Wavelength Multiplexing

A novel dual-loop optoelectronic oscillator (OEO) with different wavelengths is demonstrated. The principle of OEO is analyzed theoretically. There is almost no beating noise due to the optical domain dual-loop with different wavelengths. In our experiment, a 20-GHz radio frequency (RF) with high quality is obtained. The phase noise of the microwave signal is measured to be -120.6 dBc/Hz at 10 kHz. The loop drift of the OEO is compensated by a fiber stretcher using phase-loop locked technology and the stability of the RF has been improved greatly. The frequency drift of the OEO system is <; ± 92.5 mHz within 3 h. A 70-dB side-mode suppression ratio is achieved. In addition, the measured linewidth is better than 2.9 mHz and the Q-factor is on the order of 10
¹²
, which confirms the high spectral purity.