Monolithic shared-mass-triaxial optical accelerometer with ultra-low noise level and crosstalk

Conventional triaxial acceleration measurements predominantly rely on assembling multiple single-axis transducers, introducing limitations such as increased device volume and misalignment errors. In this paper, we demonstrate a monolithic shared-mass-triaxial optical accelerometer that integrates a compact size with ultra-low noise and crosstalk. The triaxial sensing structure employs a shared proof mass, achieving significant miniaturization compared to conventional multi-chip assembled triaxial optical accelerometers. In-plane sensing is realized through folded spring beams, while out-of-plane detection utilizes U-shaped cantilever beams with widened central segments to suppress cross-axis sensitivity and enhance mechanical responsivity. Experimental results demonstrate an operational bandwidth of 1–35 Hz, a minimum detectable acceleration of 4.12 ng / √ Hz , and a crosstalk along the Z -axis below 0.023%. The compact sensor size measures 16 mm ×16 mm ×0.5 mm . To our knowledge, this device represents the first monolithic shared-mass-triaxial optical accelerometer to successfully integrate a small size with extremely low noise and low crosstalk. This optical accelerometer achieves nano-g resolution in the triaxial direction, and its capability was validated by successfully capturing a magnitude 5.3 earthquake event with envelope waveforms consistent with a co-located commercial seismometer, demonstrating strong potential for seismic wave detection and other precision vibration monitoring fields.