  Silicon carbide (SiC) exhibits excellent material properties attractive for
broad applications. We demonstrate the first SiC optomechanical microresonators
that integrate high mechanical frequency, high mechanical quality, and high
optical quality into a single device. The radial-breathing mechanical mode has
a mechanical frequency up to 1.69 GHz with a mechanical Q around 5500 in
atmosphere, which corresponds to a mechanical f-Q product as high as 9.47x10^12
Hz. The strong optomechanical coupling allows us to efficiently excite and
probe the coherent mechanical oscillation by optical waves. The demonstrated
devices, in combination with the superior thermal property, chemical inertness,
and defect characteristics of SiC, show great potential for applications in
metrology, sensing, and quantum photonics, particularly in harsh environments
that are challenging for other device platforms.
