ALL-SILICON IN-PLANE OPTICAL ACCELEROMETER BY SILICON ELECTROCHEMICAL MICROMACHINING: DESIGN, SIMULATION, AND FABRICATION

In this work an all-silicon in-plane optical accelerometer for low-frequency applications (below 150 Hz) with high-sensitivity (about 10 μm/G) and good resolution (about 100 μG) is designed and simulated using Finite Ele- ment Method (FEM), and fabricated by silicon electrochemical micromachining (ECM) technology. The proposed accelerometer consists of a proof-mass suspended by four springs anchored to bulk silicon, and in- tegrating on opposite sides one-dimensional photonic crystal (1D-PhC) micromirrors, with additional on-chip U- grooves featuring end-point stoppers for readout optical fibers positioning. Reducing in-plane footprint of the proof-mass over a factor 12 with respect to standard silicon-on-insulator (SOI) technology, though not affecting the accelerometer sensitivity, is the major challenge overcome as a result of ECM accuracy in microstructuring at high aspect ratio values. The device is designed to work in differential mode on optical signals reflected by two Fabry-Pérot (FP) cavities exploited to transduce the proof-mass displacement into optical signals. Optical charac- terization will be carried out to compare theoretical and experimental performance of the proposed accelerometer.