Research On Optoelectronic Oscillator Based On Stimulated Brillouin Scattering

In the 21 st century,human society communication methods are undergoing rapid changes.With the development of optical fiber technology and optical communication technology,information technology using light as a transmission carrier flourishes.Optical fiber transmission is widely used in wireless transmission networks,fiber-optic communication systems,radar,defense,and military because of its large capacity,long distance,and low loss.As an ideal microwave signal generating device,the signal generated by the optoelectronic oscillator has the advantages of low phase noise,wide tunable range,anti-electromagnetic interference,high spectral purity,etc.,and has broad prospects in practical applications.This thesis introduces a system based on the stimulated Brillouin scattering filter,the output RF signal is fed back to the electro-optic modulator.An optoelectronic oscillator based on stimulated Brillouin scattering is designed and studied.The optoelectronic oscillator adopts the Brillouin scattering effect to filter and select the optoelectronic frequency in the optical domain,which avoids the noise introduced by the electric filter.By changing the wavelength of the signal light or the pump light,the output signal frequency can be adjusted in a wide frequency range.The single-frequency and dual-frequency optoelectronic oscillators are obtained experimentally,the oscillation signal is stable,and the spurious noise is weak,which is an ideal microwave signal source.Firstly,the background and current status of the optoelectronic oscillator are briefly introduced.The concepts of the oscillator's starting condition,phase noise characteristics and cavity parameters are theoretically analyzed,and the definition and the performance parameters of stimulated Brillouin scattering is explained in detail.The third part of the thesis introduces a tunable single-frequency optoelectronic oscillator based on stimulated Brillouin scattering.Based on the theoretical analysis of stimulated Brillouin scattering,the principle of the microwave photonic filter is analyzed with the mathematical derivation process,and the characteristics of the frequency response of the microwave photonic filter based on stimulated Brillouin scattering is simulated.A tunable oscillation signal with a 35 dB out-of-band rejection ratio is experimentally obtained,and the experiment results are agreed with the simulated results very well.In the fourth part of the thesis,a tunable dual-frequency optoelectronic oscillator system based on stimulated Brillouin scattering is proposed.By modulating pump light to achieve carrier-suppressed double-side-band modulation,a dual-passband microwave photonic filter is realized.Based on the dual-passband microwave photonic filter,a tunable dual-frequency optoelectronic oscillator is realized.In the experiment,a low-noise dual-frequency oscillation signal with a frequency tuning range from 0 to 20 GHz and a higher out-of-band rejection ratio is obtained.The research of the subject has laid a good foundation for the future development of optoelectronic oscillators.