Theoretical and experimental research of coupled optoelectronic oscillators

In order to study coupled optoelectronic oscillators (COEO) further, the mode selection theory of COEO was expounded. The phase matching condition to maintain optimum mode-locked state was given. The affecting factors of phase noise of radio frequency signal were analyzed. The experiment of COEO based on polarization-maintaining mechanism was conducted. By adjusting the polarization-maintaining variable optical fiber delay lines in the optical ring cavity and the optoelectric microwave oscillation loop to change the cavity length, the relationship between cavity length and oscillation frequency was obtained. Meanwhile, by using the frequency discrimination method, phase noise performances of 5GHz radio frequency(RF) signals under different operating conditions were measured and the effective factors were studied. The experimental results demonstrate that oscillation mode depends on the cavity length of optical ring cavity. Optical signal polarization, phase matching and loop length have influence on the phase noise of the RF signals. The coupled optoelectronic oscillator of 5GHz RF signal and phase noises of -136dBc/Hz at 10kHz offset frequency is obtained, whose phase noise is the lowest in our country as far as we know.