Toward navigation-grade optomechanical accelerometers on a chip

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Abstract
Acceleration sensing underlies a wide range of commercial and scientific technologies, yet optomechanical accelerometers, despite their impressive displacement sensitivity, have not reached practical viability for commercial or defense applications. Most optomechanical sensors are sensitive to external non-inertial forces, vibrations, temperature drift, and wavelength drift. In the case of the photonic integrated optomechanical accelerometers, these effects are primary sources of bias instability and limit the ability of these sensors to attain navigation-grade performance. We present a photonic integrated, fiber-packaged optomechanical accelerometer that advances toward navigation-grade accelerometry, especially with regard to bias instability. Displacement readout is provided by an integrated differential strain-sensing Mach–Zehnder interferometer attached to an ultra-rigid, bulk-micromachined proof mass with a 93.4 kHz fundamental resonance frequency (22.5 pm/g displacement). The high displacement sensitivity provides a 4.2 μg/Hz acceleration resolution over a 66 kHz operational bandwidth. Furthermore, we show that the combination of high rigidity and intrinsic differential optical readout makes the device insensitive to the common causes of bias instability, and we measure a bias instability of 6.3 μg at 243 s. The device operates over a temperature range of greater than 20 °C and a 17 nm optical bandwidth, eliminating the need for sophisticated laser sources, providing a pathway to reduced size, weight, and power. Our device is well suited for operation in practical environments and establishes a pathway for chip-scale optomechanical accelerometers to approach and potentially surpass the performance of existing chip-scale accelerometer platforms.
Funding Information
  • Department of Energy National Nuclear Security Administration Laboratory Residency Graduate Fellowship (DE-NA0003525)

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