An optomechanical MEMS geophone with a 2.5 ng/Hz^(1/2)noise floor for oil/gas exploration  

作　　者：Shimin Jiao Ziqiang Qu Xujin Ma Hao Ouyang Wen Xiong Shaolin Zhang Qiu Wang Huafeng Liu 

机构地区：[1]PGMF and School of Physics,Huazhong University of Science and Technology,Wuhan 430074,China [2]Optics Valley Laboratory,Hubei 430074,China

出　　处：《Microsystems & Nanoengineering》2024年第6期123-132,共10页微系统与纳米工程(英文)

基　　金：supported by the National Key Research and Development Program of China(grant number:2021YFB3201603);the Joint Fund of the Ministry of Equipment Development and Education(8091B032235);the Offshore Oil/Gas Exploration National Research Center Foundation(grant number:CCL2022RCPS0792RQN);the National Natural Science Foundation of China(grant numbers:42274228 and T2322008)。

摘　　要：High-precision geophones play crucial roles in terrestrial applications such as oil and gas exploration as well as seismic monitoring.The development of optomechanical precision measurements provides a new design method for geophones,offering higher sensitivity and smaller dimensions compared to traditional geophones.In this work,we introduce an optomechanical microelectromechanical system(MEMS)geophone based on a plano-concave Fabry‒Perot(F–P)microcavity,which has a high sensitivity of 146 V/g.The F‒P microcavity consists of a movable mirror on the sensing element and a fixed hemispherical micromirror fabricated from silicon-on-insulator(SOI)and monocrystalline silicon wafers,respectively.The experimental results show that the geophone has a low noise floor of 2.5 ng/Hz^(1/2)(with a displacement noise floor of 6.2 fm/Hz^(1/2))within the frequency range of 100~200 Hz,a broad bandwidth of 500 Hz(–3 dB),and a measurement range of±4 mg.To mitigate common-mode noise originating from the laser source and environmental factors such as temperature and air fluctuations,a balanced detection method is employed.This method substantially reduces the noise floor,nearly reaching the thermal noise limit(2.5 ng/Hz^(1/2)).Furthermore,a compactly packaged optomechanical MEMS geophone with a diameter of 40 mm is demonstrated.The high performance and robust features hold great potential for applications in oil and gas exploration.

关 键 词：noise MIRROR FLOOR 

分 类 号：TN2[电子电信—物理电子学]