Research On Optoelectronic Oscillator And Its Stability

With the development of photoelectric technology, the technology of the optical communication plays a more important role in the fields of aerospace, optical fiber communication, radar and so on. As the core device of the photoelectric technology, the signal source has received more attention from the researchers. The optoelectronic oscillator is one kind of signal source which has the RF output with high Q value, high spectral purity, and low phase noise. It has developed greatly owing to the efforts of researchers all around the world.In this thesis, the structure of the classic single ring OEO is firstly introduced. We analyze the oscillation threshold, linearization of the electro-optic modulator’s response function and noise to signal ratio of the OEO. The working principle of some other classic OEO structures are analyzed, and the advantages and disadvantages of their performance are compared.By researching and analyzing the OEO technology, an optoelectronic oscillator with a new structure is presented, which uses a Fiber Bragg Grating (FBG) and an FBG-based Fabry-Perot (F-P) filter as mode selectors. The utilization of EDFA, FBG and F-P filter produces the stable signal, reduces the intensity noise of the laser source. The structure utilizes the same F-P filter twice to improve the spectral purity and the long-term stability of the whole system. The phase noise of the OEO is measured down to-109dBc/Hz at10kHz offset of the RF8.97GHz output. And the side mode suppression ratio can reach-50dB. Under the laboratory condition, the entire system which runs9hours, has the center frequency drift of±2ppm. Experimental results demonstrate a stable OEO with low phase noise.Finally, the long-term stability of the OEO is analyzed. We analyze the effects of the change of the ambient temperature on the refractive index of fiber and the RF filter. The methods to improve long-term stability of the OEO are analyzed. We analysis a structure which uses the piezoelectric ceramic to adjust the length of the fiber to improve the long-term stability of the OEO.