Research On Optoelectronic Oscillators Based On Injection Locking

Microwave photonics is an emerging interdisciplinary subject.With the rapid development of optoelectronic technology,optical communication technology plays an increasingly important role in instrument measurement,radar detection,aerospace and other fields.As a new type of oscillator combining traditional microwave technology and photonic technology,the optoelectronic oscillator can output microwave signals with high Q value,high spectral purity,good stability and low phase noise,which is widely favored by scholars at home and abroad.Based on the background of the project,this paper has conducted in-depth research on OEO.Firstly,the paper introduces the principle of single-ring OEO and various typical models of OEO with improved side-mode suppression ratio.The characteristics of spectrum and phase noise of the OEO are simulated and analyzed theoretically.It is concluded that the OEO can reduce phase noise by designing the length of fibers.In order to solve the problem that it is difficult for OEO to achieve both low phase noise and large mode interval at the same time,a dual-loop OEO structure is proposed.It can improve the side-mode suppression ratio and optimize the phase noise performance.Then,the method is verified through simulation.Then the theoretical model of phase noise of injection-locked OEO is established.The SIL OEO and DSIL OEO are compared based on IL structure.The simulation shows that the SIL oscillator can reduce the phase noise by increasing the delay time and the injection intensity,and the DSIL oscillator has significant advantages in suppressing the side mode.The SIL and SPLL are combined to verify that the SILPLL OEO has the advantage of maintaining low phase noise and high frequency stability.At last,the frequency multiplier of injection-locked OEO in the X-band is carefully designed in this paper.We propose two schemes to obtain 10 GHz output frequency from100 MHz crystal oscillator.One is that we use a step recovery diode(SRD)to design one hundred times frequency multiplier,while the other is to use nonlinear transmission line(NLTL).After simulation and experiment,the spectrum and phase noise curves of the two schemes are obtained,and the 10 GHz multiplier of injection-locked OEO is designed and developed successfully.