Title: Efficient anchor loss suppression in coupled near-field optomechanical resonators,
Abstract: Elastic dissipation through radiation towards the substrate is a major loss
channel in micro- and nanomechanical resonators. Engineering the coupling of
these resonators with optical cavities further complicates and constrains the
design of low-loss optomechanical devices. In this work we rely on the coherent
cancellation of mechanical radiation to demonstrate material and surface
absorption limited silicon near-field optomechanical resonators oscillating at
tens of MHz. The effectiveness of our dissipation suppression scheme is
investigated at room and cryogenic temperatures. While at room temperature we
can reach a maximum quality factor of 7.61k ($fQ$-product of the order of
$10^{11}$~Hz), at 22~K the quality factor increases to 37k, resulting in a
$fQ$-product of $2\times10^{12}$~Hz.