Research On Key Technologies Of MOEMS Accelerometer

As one of the most important inertial components,an accelerometer is widely used in industrial production,scientific research,modern military use,and daily life.Micro-Optic-Electro-Mechanical Systems(MOEMS)accelerometer,as the next generation of MEMS accelerometer,conforms to the development trend of high-prec ision,miniaturization,and chip type,making it the worldwide research hotspot.The existing technical solutions for MOEMS accelerometers cannot meet the requirements of high precision,large dynamic range,and miniaturization at the same time.This thesis combines photonics technology and Micro/nano processing technology to carry out research on the key technologies of MOEMS accelerometers,which breaks through the contradiction between the accelerometer's accuracy and size and realizes the high precision,miniaturization,and chip type of the accelerometer This work has important scientific significance and application value.This thesis focused on the following aspects:(1)The overall scheme of the MOEMS accelerometer based on the Michelson interferometer structure is proposed.Based on the basic theory of the MOEMS accelerometer,the theoretical analysis of the accelerometer is carried out,and the theoretical model of the sensitivity and resonance frequency is established.On the basis of the principle of light polarization and interference,the polarization-related error model of the accelerometer with a wide-spectrum light source is derived using coherence matrix and Jones matrix,which verifies the feasibility of measuring acceleration with the full-polarization Michelson interferometer detection system.The simulation results show that the accelerometer has a resolution of 10-7g and a measurement range of greater than±100g under the condition that the size of the accelerometer's sensitive unit is 7.5×3×0.42mm3 and the detection accuracy is 10-7 rad.The proposed scheme is able to meet the application requirements of high precision,large dynamic range,and miniaturization.(2)This thesis has carried out research on the technology of the MOEMS accelerometer.A technical proposal of using Lithium Niobate on Silicon as the material of the accelerometer chip is proposed.Combining the respective advantages of silicon and lithium niobate materials,the accelerometer chips are developed through photonics technology and Micro/nano processing technology.This work has achieved the monolithic integration of the accelerometer,including polarization controller,phase modulator,Michelson interferometer sensing optical path,and sensitive unit microstructure.The difficulties of polarization control in the sensing optical path are effectively solved,and the polarization-related errors of the interference system are obviously suppressed.The simulation results show that the polarization-related error of the interference system is on the order of 10-8 rad,when the polarization extinction ratio of the interferometer optical path is 80dB.(3)Based on the coupled mode theory,a compact mode spot converter for MOEMS accelerometers is designed and fabricated,which solves the problem of the coupled package miniaturization of MOEMS accelerometers and reduces coupling loss.(4)The signal modulation,demodulation,and acquisition system of the MOEMS accelerometer are built,and the performance test of the prototype is completed.The test system uses double closed loops for feedback control and real-time monitoring and compensation of feedback loop gain errors,aiming to reduce the drift of the micro-optic electromechanical accelerometer caused by the changes in ambient temperature.The experimental results show that the size of the prototype of the accelerometer is 20×4×0.42mm3,the sensitivity is 1.01rad/g,the equivalent acceleration noise is 10-6g·Hz-1/2 magnitude,and the mechanical resonance frequency is about 400Hz.