Research On Excitation Source And The Integration Of Integrating Sphere And Microwave Cavity

Atomic clocks are devices based on the resonant excitation of atoms or ions to obtain time and frequency standards,it is the core of navigation and positioning,time keeping,timing and mobile communication equipment,it is widely used in national defense,commercial and civil fields.Integrating sphere cold atom clock is a miniaturized cold atomic clock,compared with the traditional hot atomic clock,its resonance spectrum is narrower and its frequency accuracy and stability are higher;Compared with other types of cold atomic clocks,its cooling mode is simple and its structure is stable.At the same time,because the atoms in the whole clock cycle act in the microwave cavity,the volume of the integrating sphere cold atom clock is very small.Therefore,integrating sphere cold atom clock has become one of the choices of space-borne clock,which has important research significance.The main work of this thesis focuses on the core devices of integrating sphere cold atom clock,and puts forward a scheme of integrating ceramic integrating sphere and microwave cavity,the results are analyzed after processing and testing;In addition,based on the index requirements of integrating sphere cold atom clock,a microwave excitation source is designed and manufactured.The specific contents are as follows:1.Filling the microwave cavity with high dielectric constant materials can reduce the volume of the cavity.Therefore,it is analyzed and demonstrated that it is feasible to make the integrating sphere with alumina ceramic materials with high purity and high laser reflectivity,so as to reduce the volume of the whole quantum system.Then the eigen equation of the integrating sphere and microwave cavity integrated device is deduced,and the relationship between the resonant frequency ofTE₀₁₁ mode and various parameters is obtained.Based on this,the integrating sphere and microwave cavity integrated device is simulated and designed.The measured S11 waveform is highly consistent with the simulation results,which proves the correctness of the overall idea.After debugging,the resonant frequency of theTE₀₁₁ mode of cavity reaches 6.834GHz.Compared with the previous resonator,the volume is reduced by more than 70%.2.According to the index requirements of integrating sphere cold atom clock,the overall scheme of microwave excitation source with DDS+PLL as the core is established.The chip selection takes into account the cost and index requirements.The feasibility of the scheme is demonstrated by estimating the phase noise and spurious of the output signal of the excitation source.The specific implementation mode and index requirements of each module of the excitation source are analyzed in detail.The microwave excitation source is manufactured according to the design scheme.The measured 6.834 GHz output signal spurious is less than-70 d Bc and the phase noise index is-53 d Bc/Hz@10Hz.It also has the ability to sweep the frequency and control the power.The integration device of integrating sphere and microwave cavity designed in this thesis has positive significance for the miniaturization of integrating sphere cold atom clock.The designed microwave excitation source has some reference function for the development of cold atomic clock.