The Performance And Design Of Optoelectronic Oscillator

Microwave signals are widely used in all areas of production and life at present, especially aviation、aerospace 、military radar and other fields requiring high quality microwave signal which make the microwave signal source become the core component of microwave system, and it is one of decisive factors of the overall microwave system performance. The microwave signal generated by the traditional microwave source is not well balance at high frequency and high-quality. Therefore, the research on new microwave source has attracted the attention of large number of domestic and foreign researchers. In recent years, several microwave signals generation technologies are proposed with the booming development of optoelectronic devices. The main content of this article is based on optoelectronic oscillator(OEO) which is optimized and expanded to obtain high frequency and low phase noise microwave signal.This article expounds the research situation and structures of optoelectronic oscillators. In addition, the working principle of optoelectronic oscillator is theoretically analyzed. This article presents a dual-loop optoelectronic oscillator with reciprocating optical path to solve a problem of optoelectronic oscillator that is a contradiction between high Q values and side mode suppression. The utilization ration of a fiber can be doubled due to feedback modulation after the optical signal passed through the modulator twice. And two optical loops with different length which are used to achieve side mode suppression can be formed in the same way. This system is able to generate microwave signal whose side-mode suppression ratio is 48.33 d B, and the phase noise is-97.35 d Bc/Hz at 10 k Hz from carrier. Moreover, the consumption of the fiber can be reduced and the control parameters are sampled since no extra active devices in this dual-loop optoelectronic oscillator are needed. The random interference and beat noise can be eliminated when the signal in the two loops transmits in opposite direction.In addition, we also propose a multi-frequency optoelectronic oscillator for costeffective which is able to generate more independent microwave signals by adding parallel filtering branches in conventional optoelectronic oscillator system, and multifrequency output are realized in this system. In the experimental demonstration, two signals with frequencies of 20 GHz and 9GHz are generated, and the side-mode suppression ratio is large than 65 d B. And the phase noise are-108 d Bc/Hz and-113 d Bc/Hz at 10 k Hz from carrier for 20 GHz and 9GHz microwave signals, respectively. This structure is not introducing additional noise, and no mutual interference between the two signals.The microwave source based on optoelectronic oscillator structure is simple and good performance, and it has wide application prospects.