In conventional micro-fabricated silicon capacitive gyroscopes, metallization is not needed if conductive doped silicon is used as the structural material. Fused Silica as a structural material is non-conductive. Therefore, a thin layer of metallization is needed to bias the resonator and excite and sense the device with capacitive electrodes.
This thin layer creates surface losses and lowers quality factor. To overcome this drawback, alternative approaches to excitation and sensing of the resonator are needed. Indirect excitation through piezoelectric material deposited on the outer shell has recently been demonstrated as a viable alternative to capacitive actuation in Dual-Shell Gyroscopes. However, no chip-level alternative to capacitive detection currently exists. In Dual-Shell resonator testing, a desktop Laser Doppler Vibrometer is used to detect displacements of the resonator from afar, by measuring the Doppler shift of a laser source focused on the surface of the vibrating shell.
Miniaturizing this approach through the use of a Photonic Integrated Circuit (PIC) will provide a chip-level alternative to sensing of the Dual-Shell resonator and circumvent surface-loss related quality factor drop, as well as bring in lower noise characteristics. To conveniently assemble high-performance single-axis inertial sensors and reference clock in a single package, “origami-like” MEMS structure is leveraged as a cointegration platform for IMU microfabrication.