TY - JOUR
T1 - Membrane-Based Optomechanical Accelerometry
AU - Chowdhury, Mitul Dey
AU - Agrawal, Aman R.
AU - Wilson, Dalziel J.
N1 - Publisher Copyright:
© 2023 American Physical Society.
PY - 2023/2
Y1 - 2023/2
N2 - Optomechanical accelerometers promise quantum-limited readout, high detection bandwidth, self-calibration, and radiation-pressure stabilization. We present a simple, scalable platform that enables these benefits with nano-g sensitivity at acoustic frequencies, based on a pair of vertically integrated Si3N4 membranes with different stiffnesses, forming an optical cavity. As a demonstration, we integrate an ultrahigh-Q (>107), millimeter-scale Si3N4 trampoline membrane above an unpatterned membrane on the same Si chip, forming a finesse F≈2 cavity. Using direct photodetection in transmission, we resolve the relative displacement of the membranes with a shot-noise-limited imprecision of 7fm/Hz, yielding a thermal-noise-limited acceleration sensitivity of 0.6μg/Hz over a 1-kHz bandwidth centered on the fundamental trampoline resonance (40 kHz). To illustrate the advantage of radiation-pressure stabilization, we cold damp the trampoline to an effective temperature of 4 mK and leverage the reduced energy variance to resolve an applied stochastic acceleration of 50ng/Hz in an integration time of minutes. In the future, we envision a small-scale array of these devices operating in a cryostat to search for fundamental weak forces such as dark matter.
AB - Optomechanical accelerometers promise quantum-limited readout, high detection bandwidth, self-calibration, and radiation-pressure stabilization. We present a simple, scalable platform that enables these benefits with nano-g sensitivity at acoustic frequencies, based on a pair of vertically integrated Si3N4 membranes with different stiffnesses, forming an optical cavity. As a demonstration, we integrate an ultrahigh-Q (>107), millimeter-scale Si3N4 trampoline membrane above an unpatterned membrane on the same Si chip, forming a finesse F≈2 cavity. Using direct photodetection in transmission, we resolve the relative displacement of the membranes with a shot-noise-limited imprecision of 7fm/Hz, yielding a thermal-noise-limited acceleration sensitivity of 0.6μg/Hz over a 1-kHz bandwidth centered on the fundamental trampoline resonance (40 kHz). To illustrate the advantage of radiation-pressure stabilization, we cold damp the trampoline to an effective temperature of 4 mK and leverage the reduced energy variance to resolve an applied stochastic acceleration of 50ng/Hz in an integration time of minutes. In the future, we envision a small-scale array of these devices operating in a cryostat to search for fundamental weak forces such as dark matter.
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U2 - 10.1103/PhysRevApplied.19.024011
DO - 10.1103/PhysRevApplied.19.024011
M3 - Article
AN - SCOPUS:85148324481
SN - 2331-7019
VL - 19
JO - Physical Review Applied
JF - Physical Review Applied
IS - 2
M1 - 024011
ER -