| Microwave oscillators have been widely applied in the field of radar, communication, measurement instruments, and so on. And its quality directly determines the overall performance of the electronic system. Opto-Electronic oscillator （OEO） is a new type of oscillator combining traditional microwave and photonic technologies. The OEO has attracted great interest due to the potential of generating ultra-low phase noise microwave signals. Compared with traditional oscillators （Crystal Mutiplied Source, Dielectric Resonator Oscillator and so on）, OEO can overcome the defect that the phase nois & of traditional microwave oscillators will be deteriorated with increasing frequency. OEO can keep ultra-low phase noise performance at microwave and millimeter wave bands. In addition, OEO is capable of generating both optical- and electrical-output signals at the same time and may be used very conveniently for a variety of optical communication systems and microwave photonic systems. However, the frequency stability of the ultra-low phase noise OEO is one of the most critical factors to decide the practical application. In this dissertation, a series of research work has been carried out and listed as follows:（1） The classical theoretical model of OEO is studied, and the relationship between the performance of OEO and the parameters of the devices is deduced by a Quasi-linear theory.（2） An injection locked OEO （IL OEO） based on microwave reference is studied. The phase noise theoretical model of the IL OEO is established. The model demonstrates the relationships among the locking bandwidth, the power and phase noise of the injection signal, and the oscillation signal power. The experimental investigations of the IL OEO indicate that an injection locking technique can significantly improve the side mode suppression ratio （SMSR）. The performance parameters of the IL OEO are measured at a constant temperature （±0.01℃）. The experimental results show that the SMSR is more than 80 dB, the single side band （SSB） phase noises are -78.8 dBc/Hz@100 Hz and -124.1 dBc/Hz@1 kHz, and the Allan deviations are 1.32×10-11@0.1 s,1.37×10-11@1s,3.12×10-11@10 s,8.1× 10-11@100 s and 1.1×10-11@1000 s, respectively. Compared with the free running OEO, The IL-OEO improves the properties of the close-in SSB phase noise and frequency stability, especially the SMSR （53.2dB）.（3） The theoretical and experimental study of an OEO based on PLL technique （PLL OEO） is performed. The PLL OEO could make up the defects of the narrow bandwidth of the IL OEO. The experimental results show that the SMSR is more than 27.1dB, the SSB phase noises are -80.3 dBc/Hz@100Hz and -124.2 dBc/Hz@1 kHz, and the Allan deviations are 1.53×10-11@0.1 s,1.65×10-11n@1s,2.11×10-11@10s, 2.32×10-11@100s and 2.51×10-11@1000 s, respectively. Compared with the free running OEO, the close-in SSB phase noise of the PLL OEO has been improved. Compared with the IL OEO, the PLL OEO has better long-term stability without the precision temperature control, however, the side mode suppression ratio is worse than52.9 dB.（4） An OEO Utilizing IL-PLL technique （IL-PLL OEO） is proposed. The IL-PLL OEO can make up the shortcomings of the IL OEO’s narrow locking bandwidth and the PLL OEO’s undesirable side-mode suppression ratio. The experimental results show that the SMSR is more than 80 dB, the SSB phase noises are -79.92 dBc/Hz@100 Hz,-125 dBc/Hz@l kHz and -143dBc/Hz@10 kHz respectively, and the Allan deviations are 1.32×10-11@0.1 s,1.37×10-11@1s,1.85×10-11@10s,1.19 ×10-11@100s and 1.22×10-11@1000 s, respectively. The experimental results indicate that the IL-PLL OEO can achieve the high SMSR, ultra-low phase noise, and high stability.
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