Phononic comb generation in high-Q quartz resonators
R. L. Kubena, Walter S. Wall, J. Koehl, R. J. Joyce
Abstract
We report on the observation of high-fidelity, high-Q, phononic combs in AT-cut 100-MHz shear-mode quartz resonators. The comb generation was observed on the first spurious mode above the fundamental mode resonance when driven a few kHz off resonance at power levels between +11 and +18 dBm. These combs exhibit the expected phase coherence between the teeth with no measurable line broadening from the nonlinear generation. Interestingly, the combs can exhibit a complex structure at particular temperatures. These changes in the comb structure over temperature are thought to be driven by the relative frequency shifts between the interacting modes. Teeth with both much larger and smaller frequency sensitivities to the drive frequency have been observed. These characteristics may be useful for enhancing the sensitivity of resonant-mode MEMS sensors or improving the phase stability of oscillators. In addition, if cryogenically cooled, these highly coherent combs may provide a component for phononic quantum processing studies.