Research On Wafer Level Preparation And Microwave Electric Field Testing Technology Of MEMS Atomic Vapor Cell

Highly sensitive amplitude detection of microwave electric fields is of great importance in areas such as communication and navigation,radar detection,and weather prediction.Quantum sensor technology based on Rydberg atomic microwave electric field measurement provides a way to receive signals without resistive participation and thus has become a hot research topic in recent years.The size of the atomic vapor cell as the core sensitive surface head of the quantum sensor plays a decisive role in the development of the integration and miniaturization of quantum sensors.In the traditional preparation methods,atomic vapor cells are mainly formed by glass bubble blowing,and their size is generally at the centimeter level,and the problems of batch and low-cost preparation need to be overcome.For the above problems,this thesis designs and prepares a MEMS atomic vapor cell with a silicon-based cavity using MicroElectro-Mechanical System(MEMS)preparation technology.The performance of the MEMS atomic vapor cell is characterized based on a two-photon excited Rydberg state differential optical path test platform,and the detection of microwave field strength was realized.The thesis first briefly describes the characteristics of microwave electric field measurements based on classical and quantum physics methods,and gives a detailed introduction to the current status of domestic and international research on atomic vapor cell.Second,the basic properties and energy level theory of alkali metal cesium atoms are briefly introduced,and a study of microwave electric field detection based on the Aulter-Townes(AT)effect is carried out based on the simulation of Electromagnetically Induced Transparency(EIT)phenomenon using the RLC circuit model.We have designed a "two-cavity" vapor cell structure to address the need for miniaturization of MEMS vapor cell,and achieved the fabrication of 5mm × 7 mm × 2 mm atomic vapor cell on 4-inch substrates and in situ encapsulation of alkali metal releasers by solving key technologies such as deep silicon etching of vapor cell cavities and anodic bonding of glass/silicon/glass triple-layer structures.The key technology was realized on a 4-inch substrate.The alkali metal release agent was activated by a laser with a power of 1W to achieve in-situ release of alkali metal elements.To characterize the MEMS atomic vapor cell,a two-photon excitation of the atomic Rydberg state is used in this paper,and a saturated absorption spectrum stable frequency detection laser optical path is constructed along with the two-photon excitation optical path of852 nm probe laser and 510 nm coupling laser.The absorption depth of the atoms at different laser powers was analyzed using photon absorption experiments,and the experimental results showed that the absorption amplitude first changed proportionally with the increase of the probe laser power,and then the amplitude gradually stabilized,which proved the existence of cesium alkali metal singlet atoms in the MEMS vapor cell.The EIT signal of the MEMS vapor cell was detected by using the probe laser differential detection method,and the reason for the change of the EIT amplitude related to the " probe laser power" was analyzed theoretically.On this basis,the microwave electric field at a frequency of 23.887 GHz is measured.The linear relationship between the EIT-AT splitting interval and the output power of the microwave source is 6.256 ± 0.240GHz/√m W,which realizes the functional verification of the MEMS atomic vapor cell.