Jeudi 16 mars à 9h30
Salle Rémy Lemaire, K223
Orateur : Marc Sansa (LETI)
"Resonance frequency fluctuations in silicon nanoresonators : a new limit of detection"
The study on nanomechanical resonators is often based on the precise determination of their frequency response, and more concretely their resonance frequency. The uncertainty of this measurement was often predicted from its intrinsic phase noise, originated by the Brownian motion of the resonator. We recently showed that no works up to now reach this theoretical limit, even though in a large number of cases Brownian motion is the dominating phase noise source. The origin of this discrepancy in crystalline silicon nanoresonators are resonance frequency fluctuations, which represent an unexpected experimental limit. We study this phenomenon using piezoresistive and optomechanic transductions, concluding that the source of frequency fluctuations intrinsic to the resonator itself. While resonance frequency fluctuations have been often considered negligible, we have shown that they may pose a widespread practical limit in the measurement of nanoresonators, and performed the first steps towards understanding of the origins of this phenomenon.