Development Of The Physical System Of The Space Optical Clock And Measurement Of The Absolute Frequency

The ⁸⁷Sr neutral fermion optical lattice clock has demonstrated high stability and accuracy performance,and the development of space optical clocks based on optical lattice clocks is of great significance for the comparison of time and frequency between space and earth,the measurement of gravitational redshift of the earth’s surface,the improvement of satellite navigation accuracy and the detection of dark matter.At the same time,the absolute frequency measurement of the optical clock can be traced back to the international atomic time,and the high stability and accuracy of the optical clock can be used to improve the accuracy of the second definition.Therefore,this thesis mainly introduces the basic principle of the ⁸⁷Sr optical clock,the building and testing of the proof-of-concept model of the space optical clock,the assembly and testing of the physical system of the actual system,and the absolute frequency measurement of the laboratorial standard optical clock.（1）The principle of ⁸⁷Sr cold atomic optical clock is introduced,including the first-stage broadband-frequency laser cooling,the second-stage narrow-linewidth laser cooling,the optical lattice loading of atoms,the clock transition spectroscopy excited by narrow-linewidth clock laser and the closed-loop locking of optical clock.The sources and measurement of the stability and uncertainty of the main indicators of the optical clock are briefly described.（2）The proof-of-concept model of the space optical clock is displayed,and the system is installed at 170 cm×60 cm×45 cm aluminum shelf.Different from the laboratorial standard optical clock,the design of space optical clock pays more attention to compactness and robustness,such as modular design,miniaturized subsystem,optimized reduced power consumption and all-fiber connection between subsystems.The physical system is placed at the size of 40 cm×55 cm×28 cm aluminum alloy frame.The clock transition spectroscopy detection and closed-loop locking of the proof-of-concept model are completed,and the system self-comparison stability is obtained.（3）The development and test of the vacuum physical system of the space optical clock actual system for flight are shown.Firstly,it introduces the basic information of the physical system,such as the size,weight,interface and main components,and then introduces the design and development of the vacuum system,and introduces the key and important components in the system that are different from the proof-of-concept model in detail.Finally,it briefly introduces the basic test of the physical system.（4）Based on the laboratorial standard optical clock system,the absolute frequency measurement of ⁸⁷Sr atomic optical clock has been completed.The upgrading and optimization of the system achieved a system uncertainty of 5.15×10^-17of ⁸⁷Sr optical lattice clock.Then it shows the uncertainty evaluation of the laboratorial optical clock,and traces the absolute frequency of the optical clock to the primary and secondary frequency standards in the BIPM time-frequency bulletin based on the satellite link,with the link transmission uncertainty of 4.1×10^-16.