Study On Modes Manipulation In High Frequency Nanomechanical Resonators

In recent years,with the development of the micro/nano processing technology,micro/nano-electromechanical systems have been widely studied.Graphene-based high frequency nanomechanical resonators,with outstanding electrical and mechanical properties,have shown great potentials in many fields of precision measurement and information processing.In this thesis,high frequency nanomechanical resonators were constructed based on few-layer graphene ribbons,and then the modes manipulation was studied.Specifically,the mode characteristics in the mechanical system were explored,mainly including the observation and the regulation of the strong coupling among multiple independent resonators and the nonlinear synchronization among the coupled modes.Besides,a gate-tunable bolometer based on the high-frequency nanomechanical resonators was realized by direct and indirect regulation of the coupled modes.The main content of this thesis includes:1.The concepts and research background of the graphene high frequency nanomechanical resonators were briefly reviewed,and the basic concepts related to strong coupling,synchronization and frequency response were briefly introduced as well.2.The nanofabrication of the samples was introduced,and the method of the measurement in this study was briefly described.3.After a sample with 5 resonators in series was prepared,the strong coupling among the modes of independent resonators was studied,and the strong coupling among up to 5resonators was realized.4.The nonlinear effect of the strongly coupled modes was studied in three independent resonators in series.Then the phenomenon of the nonlinear synchronization was observed,and furthermore,the synchronization was regulated by tuning the coupling strength which was in dependence on the intermediate resonator.And it was notable that two different forms of synchronization had been observed in the experiments.5.A dual-bolometer was realized by two coupled graphene resonators.Moreover,the sensitivity and response bandwidth were regulated directly and indirectly by the gatetunability.The main innovations of this thesis are:1.The strong coupling among 5 independent resonators provided the basis for phononic waveguide construction and long-range phonon information processing.2.The observation of the nonlinear synchronization phenomena and the adjustment of the synchronization by tuning the coupling strength provided a possible perspective for in-depth study of nonlinear dynamics.3.The bolometer with the performance directly and indirectly tunable laid the foundation for the development of large-scale sensing arrays.