Optoelectronic Oscillator Research Based On Multi-wavelength Pumping

Microwave photonics,as an emerging discipline,integrates the advantages of optoelectronics and microwave technology to provide new solutions to technical challenges in optoelectronics and microwave fields.An important direction in microwave photonics is photogenerated microwave,and optoelectronic oscillator（OEO）,as an important method in photogenerated microwave technology,provides new options for the generation of high frequency,low phase noise,and tunable microwave signals.In this paper,a multi-wavelength pumping-based OEO-related study is carried out using the fiber-optic stimulated Brillouin scattering（SBS）effect.The main work contents are as follows.According to the basic structure of OEO a theoretical derivation is carried out and the relationship between oscillation frequency and loop delay is analyzed,and the influencing factors of phase noise are explored.The basic principle of electro-optical modulator is given,and the theoretical derivation of the output optical field after the light wave is modulated by the electro-optical modulator is presented.The basic theory of SBS is described,and the Brillouin gain spectral characteristics and the influencing factors of Brillouin threshold are analyzed.A theoretical analysis of multi-wavelength-based microwave photonic filter（MPF）and SBS-and phase-modulation-based MPF is carried out,and simulation studies are conducted to conclude that the SBS-and phase-modulation-based MPF is easier to achieve narrow-band filtering.The frequency response characteristics of the single wavelength pumped MPF based on a single light source are explored,and the OEO structure is designed.Experimentally,the photogenerated microwave signal is tunable in the range of 10.13-10.65 GHz,while the characteristics of the output microwave signals are compared and analyzed with the OEO based on the single wavelength pumped OEO with a dual light source,and the output microwave signal of the OEO based on a single light source MPF is more stable.In the 20min test time,the frequency of the output microwave signal does not change at 1MHz resolution,and the intensity change is 1.15d B.The theoretical analysis and simulation of the MPF based on multi-wavelength pumping are carried out,and verified through experiments,the results show that the MPF can obtain a dual passband frequency response with equal amplitude when dual-wavelength pumping light is used.The experimental structure of OEO based on single-source modulated multi-wavelength pumping is designed,and the principle of dual-band microwave signal generation is analyzed.At f_RF=3GHz,high-frequency signals of 7.48GHz and 13.48GHz are obtained,and the out-of-band rejection ratio is about 29d B,and the tuning of dual-band microwave signals is achieved by changing the f_RF.The structure of OEO based on dual-source modulated multi-wavelength pumping is designed.At f_RF=3GHz,high-frequency signals of 4.02GHz and 10.02GHz are obtained,keeping the pump light wavelength constant and changing the f_RF to obtain microwave signals with adjustable frequency interval and symmetry about 7.02Ghz;when f_RF is constant,the dual-frequency interval is constant,when changing the pump light wavelength makes the OEO output microwave signal tunable.