Motion transduction with suspended Graphene resonators

Detecting motion with high precision has been a fundamental pursuit in science for detecting new forces and in technology, towards developing new forms of sensors, oscillators or computational tools. Here we report a suspended Graphene resonator as a tunable, broad-bandwidth motion detector with high sensitivity at room temperature. As a proof-of-concept experiment, we use a large area Silicon Nitride (SiN) as a target oscillator. Intrinsic, elastic coupling of suspended Graphene resonator to SiN is measured to be in the strong-coupling regime. When the SiN resonator is excited photo-thermally, we measure an average gain of 38 dB in Graphene displacement power spectrum. The corresponding detection sensitivity is 33 fm/√Hz, with a detector back-action of 28 fN/√Hz while a moderate improvement in signal-to-noise ratio of 3.6 dB is limited primarily by Graphene Brownian motion. Thermomechanical squeezing of noise further improves the sensitivity by a factor of 4. With growing usage of high-quality factor SiN resonators as hybrid opto-mechanical elements, such Graphene-based motion transducer can significantly aid in detecting their motion, due to forces at the level of few photons.