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Abstract

We report on the progress of our novel low-frequency optomechanical inertial sensing technologies for gravimetry and space geodesy. Our technologies are designed to be compact, portable, and are comprised of monolithically fabricated mechanical resonators that incorporate compact and highly sensitive laser interferometric displacement sensors.Current laboratory prototypes have demonstrated mechanical quality factors Q of 4.77x10⁵, an mQ-product above 1200 kg, a fundamental mechanical resonance of 4.7 Hz, which highlight their high sensitivity with acceleration noise floor nears 1x10^-11 m s^-2/√Hz. Such compact systems are excellent candidates for future applications in gravimetry, geodesy, geophysics, and hydrology.A prototype packaging has been developed to reduce losses caused by typical mechanical mounts. We have conducted comparison measurements with commercial low-frequency systems to an excellent agreement. Recent measurements taken with the resonator mounted in this packaging atop a vibration isolation platform have indicated that our system is seismically limited above 1 mHz. Noise floors in the order of 82 pico-g/√Hz at 0.4 Hz has been demonstrated in our laboratory.We will present recent updates on our optomechanical inertial sensors, including up to date measurements of the resonator and interferometer sensitivity, as well as that of the combined system.