Nano-optomechanical silicon accelerometer for high performance applications

Published : 28 June 2020

Inertial sensors (accelerometers and gyrometers) are at the heart of a large number of consumer-and low-cost applications such as smartphones and tablets, but also higher added value, higher-performance applications such as navigation for autonomous vehicles, aeronautics or space. Silicon microsystems (MEMS) are today a very mature technology and several millions are sold each year. However, they are today unable to address high-performance applications.

LETI has been pioneering the development of optomechanical sensors “on-chip”: light is guided in thin silicon layers in a similar way to photonics techniques. This light interacts with an object in motion such as a mechanical resonator or a seismic mass. This displacement modulates the intensity of the measured light, which allows the determination of the object’s acceleration. This technology was developed in the 2000s in fundamental research, and in particular enabled gravitational wave detectors. LETI is developing this technology on-chip at the nanoscale, with displacement sensitivities several orders of magnitude better than electrical transductions.

First optomechanical accelerometers were designed and fabricated in LETI’s quasi-industrial clean rooms for initial characterization tests. The hired fellow with have to become familiar with these devices, to confirm the first optical results, and then most importantly to assess their performances under acceleration: a test setup will have to be realized for this purpose. She or he will have to provide feedback on the modeling and the design from the measurements in order to ensure the comprehension of all phenomena at play. Finally, the postdoctoral fellow will have to propose new designs aimed at the expected high performances. These devices will be fabricated by the clean room, tested by the fellow and and compared to the expected performance.

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