A capacitive-gap transduced micromechanical ring resonator based on a radial contour vibration mode and constructed from hot filament CVD boron-doped microcrystalline diamond has achieved a Q of 42,900 at 2.9685GHz that represents the highest series-resonant Q yet measured at this frequency for any on-chip room temperature resonator, as well as the highest f Q of 1.27×10 14 for acoustic resonators, besting even macroscopic bulk-mode devices. Values like these in a device occupying only 870μm 2 may soon make possible on-chip realizations of RF channelizers and ultra-low phase-noise GHz oscillators for secure communications.

A Radiation Pressure driven Optomechanical Oscillator (RP-OMO) comprised of attached concentric rings of polysilicon and silicon nitride has achieved a first demonstration of a mixed material optomechanical device, posting a mechanical Q m of 22,300 at 52 MHz, which is more than 2× larger than previous single-material silicon nitride devices [1]. With this Q m , the RP-OMO exhibits a best-to-date phase noise of -125 dBc/Hz at 5 kHz offset from its 52-MHz carrier-a 12 dB improvement from the previous best by an RP-OMO constructed of silicon nitride alone [1]. The key to achieving this performance is the unique mechanical Qboosting design where most of the vibrational energy is stored by the high-Q m polysilicon inner ring which in turn boosts the overall Q m over that of silicon nitride, all while retaining the high optical Q o >190,000 of silicon nitride material. Simultaneous high Q o and Q m reduces the optical threshold power for oscillation, allowing this multi-material RP-OMO to achieve its low phase noise with an input laser power of only 3.6 mW.

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