Lu Qianbo, Wang Chen, Bai Jian, Wang Kaiwei, Lou Shuqi, Jiao Xufen, Han Dandan, Yang Guoguang, Liu Dong, Yang Yongying
Opt Express. 2016 Apr 18;24(8):9094-111. doi: 10.1364/OE.24.009094.
Cross-axis sensitivity of single-axis optomechanical accelerometers, mainly caused by the asymmetric structural design, is an essential issue primarily for high performance applications, which has not been systematically researched. This paper investigates the generating mechanism and detrimental effects of the cross-axis sensitivity of a high resoluion single-axis optomechanical accelerometer, which is composed of a grating-based cavity and an acceleration sensing chip consisting of four crab-shaped cantilevers and a proof mass. The modified design has been proposed and a prototype setup has been built based on the model of cross-axis sensitivity in optomechanical accelerometers. The characterization of the cross-axis sensitivity of a specific optomechanical accelerometer is quantitatively discussed for both mechanical and optical components by numerical simulation and theoretical analysis in this work. The analysis indicates that the cross-axis sensitivity decreases the contrast ratio of the interference signal and the acceleration sensitivity, as well as giving rise to an additional optical path difference, which would impact the accuracy of the accelerometer. The improved mechanical design is achieved by double side etching on a specific double-substrate-layer silicon-on-insulator (SOI) wafer to move the center of the proof mass to the support plane. The experimental results demonstrate that the modified design with highly symmetrical structure can suppress the cross-axis sensitivity significantly without compromising the sensitivity and resolution. The cross-axis sensitivity defined by the contrast ratio of the output signal drops to 2.19% /0.1g from 28.28%/0.1g under the premise that the acceleration sensitivity of this single-axis optomechanical accelerometer remains 1162.45V/g and the resolution remains 1.325μg.
单轴光机械加速度计的交叉轴灵敏度主要由不对称结构设计引起，这对于高性能应用来说是一个至关重要的问题，但尚未得到系统研究。本文研究了一种高分辨率单轴光机械加速度计交叉轴灵敏度的产生机制及其有害影响，该加速度计由基于光栅的腔体和一个加速度传感芯片组成，传感芯片包含四个蟹形悬臂梁和一个检测质量块。基于光机械加速度计交叉轴灵敏度模型，提出了改进设计并搭建了原型装置。在这项工作中，通过数值模拟和理论分析，对特定光机械加速度计的交叉轴灵敏度在机械和光学组件方面进行了定量讨论。分析表明，交叉轴灵敏度会降低干涉信号的对比度和加速度灵敏度，还会产生额外的光程差，这会影响加速度计的精度。通过在特定的双衬底层绝缘体上硅（SOI）晶圆上进行双面蚀刻，将检测质量块的中心移至支撑平面，实现了机械设计的改进。实验结果表明，具有高度对称结构的改进设计能够在不影响灵敏度和分辨率的前提下，显著抑制交叉轴灵敏度。在该单轴光机械加速度计加速度灵敏度保持为1162.45V/g且分辨率保持为1.325μg的前提下，由输出信号对比度定义的交叉轴灵敏度从2 /0.1g降至2.19% /0.1g。 8.28%
