Research On Microwave Photonic Filters Based On Stimulated Brillouin Scattering And Related Application

Compared with the traditional microwave filter,MPF has the advantages of large bandwidth,strong anti-electromagnetic interference ability,and has a large tunable range in the high frequency band,the shape and bandwidth of the filter can be reconfigurable,etc.Stimulated Brillouin scattering(SBS)can excite the gain spectrum and loss spectrum with very narrow bandwidth,which makes the MPF based on SBS have very high resolution.Through precise design and control of pump light,the filter bandwidth and passband shape can be flexibly reconstructed.Therefore,it is of great significance to study the MPF based on SBS.In this thesis,MPF based on SBS and its application in optoelectronic oscillator(OEO)are studied.Firstly,the development background,research status and basic principle of microwave photonic filter are introduced.And on this basis,the SBS effect and frequency shift measurement scheme are introduced,and then the single-passband MPF and dual-passband tunable MPF based on SBS are proposed,and the theoretical analysis and experimental verification are carried out.Finally,we apply it to OEO and propose freely tunable single-frequency OEO and dual-frequency OEO based on SBS.The work of this paper is as follows:1.A tunable single passband MPF is proposed and a tunable single frequency OEO is realized.The scheme is based on a single light source,adopts electro-optic frequency shift method,and uses the gain spectrum of SBS effect as the optical filter.The system has good stability.A single passband frequency response with 3d B bandwidth of 50 MHz,out of band rejection ratio exceed 30 d B and a single frequency signal with side mode rejection ratio exceed 35 d B are obtained.By adjusting the frequency of the RF signal loaded on the Dual parallel Mach Zehnder modulator(DPMZM)of pump optical branch,a tunable single pass band MPF in the range of1.33GHz?7.33 GHz is obtained,and a tunable single frequency signal in the range of3.33GHz-8.33 GHz is generated.2.A free tunable dual passband MPF is proposed and a tunable dual band OEO is realized.According to the two Brillouin gain spectra located on either side of the optical carrier or the same side of the optical carrier,theoretical analysis and experimental verification are carried out respectively.When the two Brillouin gain spectra are located on each sides of the optical carrier,by adjusting the frequency of the RF signal loaded on the DPMZM in the signal and pump branches,a freely tunable dual pass band MPF in the range of 1.288GHz?14GHz with 3d B bandwidth of 54 MHz and out of band rejection ratio exceed 23 d B is obtained;A freely tunable dual frequency signal with side mode rejection ratio exceed 20 d B and tunable range of 1.288 GHz to 14 GHz is generated.When the two Brillouin gain spectrums are located on the same side of the optical carrier,by adjusting the frequency of the RF signal loaded on the DPMZM in the signal optical and pump optical branches,a freely tunable dual pass band MPF in the range of 1.712GHz?15GHz with 3d B bandwidth of 54 MHz and out of band rejection ratio exceed 23 d B is obtained;A freely tunable dual frequency signal with side mode rejection ratio exceed 20 d B and tunable range of 1.712 GHz to 17 GHz is generated.