Monolithic Silicon Photonics Interferometer for Ultra-sensitive MEMS Sensors

用于超灵敏 MEMS 传感器的单片硅光子干涉仪

• 批准号: ST/M000427/1
• 负责人: Giles Hammond
• 金额: $ 6.31万
• 依托单位: University of Glasgow
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=ST%2FM000427%2F1
• 关键词: Monolithic; Silicon; Photonics; Interferometer; Ultra

Interferometers are devices which can provide accurate position measurements. They work by comparing the distance travelled by light in two (typically) perpendicular arms. When the light from the two beams is combined and interfered, the change in intensity can be compared to a fraction of the wavelength of light. If both light waves are in-phase the light output is a maximum, while if the light waves are out of phase the intensity will be zero. This project will develop a miniaturised on-chip interferometer suitable for use in Micro-Electro-Mechanical System (MEMS) sensors. The entire interferometer will occupy a size below 10 mm x 10 mm. The light source will be an off-chip 1550 nm laser which is coupled to on-chip silicon waveguides, polarising beamsplitters and Ge photodetectors which are fabricated by reactive ion etching of commercial silicon-on-insulator (SOI) wafers. The interferometer utilises the polarisation of the incoming laser beam to operate two separate interferometers within the same Si components. This is achieved by shifting one of the beams by 90 degrees with respect to the other one with a phaseplate. By plotting the two outputs from the interferometer we achieve a circular pattern whereby the circle is traversed every time the mirrors are moved a relative separation equal to one half the wavelength of light (or lambda/2). If the circle can be subdivided into 1000 sections, the sensitivity is of the order 700 picometres for 1550 nm laser light. In principle it is possible to do even better by accurate modelling of the shape of the resulting circular pattern and we propose to demonstrate a sensitivity of 100 picometres.Current MEMS sensors are typically monitored with simple electrostatic sensors which measure the capacitance between micro-structured electrodes. Whilst being a relatively simple component, this method has limitations in the achievable sensitivity, and also challenges as electrostatic voltage causes spurious forces which can destabilises the delicate MEMS device and cause it to lock. The on-chip interferometer which is described in this proposal will be combined with a MEMS accelerometer in order to provide an ultra-sensitive device able to sense tiny changes in gravity. To give quantitative measure of the sensitivity, MEMS accelerometers found in iPhones typically have an acceleration sensitivity of 0.015 ms-2 and are able to sense the direction of the screen. The accelerometer we propose here has sensitivity approximately 1 million times better than an iPhone accelerometer. This will allow the opportunity to utilise the optical readout MEMS to monitor the gravitational effects of a variety of bodies. This could include dense objects being smuggled through ports of entry, hidden subterranean tunnels, the location of carbon sequestered under the ground or the location of buried nuclear waste. The device thus has a wide range of applications in the areas of precision sensing and monitoring, detecting hidden dense masses and buried objects/tunnels, and the monitoring of carbon/nuclear waste in geological repositories.

干涉仪是可以提供精确位置测量的设备。他们的工作原理是比较光在两个（通常）垂直臂中传播的距离。当来自两束光的光被组合和干涉时，强度的变化可以与光的波长的一小部分进行比较。如果两个光波同相，则光输出最大，而如果光波异相，则强度将为零。该项目将开发一种适用于微机电系统（MEMS）传感器的嵌入式片上干涉仪。整个干涉仪的尺寸将小于10 mm x 10 mm。光源将是一个1550 nm的片外激光器，它与片上硅波导、偏振分束器和Ge光电探测器耦合，这些器件是通过对商业绝缘体上硅（SOI）晶片进行反应离子蚀刻制造的。干涉仪利用入射激光束的偏振来操作相同Si组件内的两个单独的干涉仪。这是通过用相位板将其中一个光束相对于另一个光束偏移90度来实现的。通过绘制干涉仪的两个输出，我们获得了一个圆形图案，由此每次移动镜子时，该圆都被横穿，相对间隔等于光波长的一半（或λ/2）。如果圆可以被细分为1000个部分，则对于1550 nm激光的灵敏度为700微微米的量级。在原则上，它是可以做得更好，通过精确建模所得到的圆形图案的形状，我们建议证明100 picometres.Current MEMS传感器的灵敏度通常是监测与简单的静电传感器，测量微结构电极之间的电容。虽然是相对简单的组件，但该方法在可实现的灵敏度方面具有限制，并且还具有挑战性，因为静电电压会导致寄生力，这会使精密的MEMS器件不稳定并导致其锁定。本提案中描述的片上干涉仪将与MEMS加速度计相结合，以提供能够感测重力微小变化的超灵敏器件。为了定量测量灵敏度，iPhone中的MEMS加速度计通常具有0.015 ms-2的加速度灵敏度，并且能够感测屏幕的方向。我们在这里提出的加速度计的灵敏度比iPhone加速度计高出约100万倍。这将允许有机会利用光学读出MEMS来监测各种物体的重力效应。这可能包括通过入境口岸走私的高密度物体、隐藏的地下隧道、地下封存的碳的位置或掩埋的核废料的位置。因此，该装置在精确传感和监测、探测隐藏的密集物质和掩埋物体/隧道以及监测地质储存库中的碳/核废物等领域有着广泛的应用。

项目成果

Field Tests of a Portable MEMS Gravimeter.

• DOI: 10.3390/s17112571
• 发表时间: 2017-11-08
• 期刊: Sensors (Basel, Switzerland)
• 作者: Middlemiss RP;Bramsiepe SG;Douglas R;Hough J;Paul DJ;Rowan S;Hammond GD
• 通讯作者: Hammond GD

A Simulation Study of the Temperature Sensitivity and Impact of Fabrication Tolerances on the Performance of a Geometric Anti-Spring Based MEMS Gravimeter

温度敏感性和制造公差对几何抗弹簧 MEMS 重力计性能影响的仿真研究

• DOI: 10.1109/inertial53425.2022.9787761
• 发表时间: 2022
• 作者: Belwanshi V

A MEMS gravimeter with multi-axis gravitational sensitivity

• DOI: 10.1109/inertial53425.2022.9787754
• 发表时间: 2021-02
• 期刊: 2022 IEEE International Symposium on Inertial Sensors and Systems (INERTIAL)
• 作者: R. Middlemiss;P. Campsie;W. Cunningham;R. Douglas;Victoria McIvor;Vinod Belwanshi;J. Hough;S. Row

A 19 day earth tide measurement with a MEMS gravimeter.

• DOI: 10.1038/s41598-022-16881-1
• 发表时间: 2022-07-29
• 期刊: SCIENTIFIC REPORTS
• 影响因子: 4.6
• 作者: Prasad, Abhinav;Middlemiss, Richard P.;Noack, Andreas;Anastasiou, Kristian;Bramsiepe, Steven G.;Toland, Karl;Utting, Phoebe R.;Paul, Douglas J.;Hammond, Giles D.
• 通讯作者: Hammond, Giles D.