A Chip-Scale Silicon Cavity Optomechanical Accelerometer With Extended Frequency Range

The integration of modern accelerometers and gyroscopes has led to the development of inertial measurement units (IMUs), which have evolved into inertial navigation systems (INS) and, more recently, into positioning, navigation, and timing (PNT) systems. Furthermore, multisensor on-chip technology is advancing, delivering wider bandwidths, heightened precision, and further miniaturization. Optomechanical sensor research reveals significant advantages over conventional accelerometers, particularly in the achievement of low-noise resonant optomechanical transduction, which approaches the thermodynamic limit. In this study, we further present a differential-type optomechanical accelerometer based on the 2-D slot-type silicon photonic crystal (PhC) microcavity from the low-frequency region to near the fundamental resonance frequency. It is demonstrated that in the parametric optomechanical oscillation mode, the silicon-on-insulator (SOI) sensor has a measured noise-equivalent acceleration (NEA) of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 20~\mu $ </tex-math></inline-formula> g/Hz<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\text {1/ {2}}}$ </tex-math></inline-formula>, nearing the thermal noise limit of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\sim 14~\mu $ </tex-math></inline-formula> g/Hz<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$^{\text {1/ {2}}}$ </tex-math></inline-formula>. The sensor, designed for broadband vibration measurements, is engineered with a theoretical bandwidth of ~70 kHz but can only be measured up to 30 kHz due to instrumentation limitations. This device is suitable for various applications such as vibration detection, inertial navigation, acoustic analysis, or optical sensing collaboration.