  Nonlinear modal interactions and associated internal resonance phenomena have
recently been used to demonstrate improved oscillator performance and enhanced
sensing capabilities. Here, we show tunable modal interaction in a MoS2
resonator. We achieve the tunability of coupling between these initially
uncoupled modes by using electrostatic gate voltages. This tunable coupling
enables us to make the modes commensurate and observe energy exchange between
the modes. We attribute the strong energy exchange between the vibrational
modes to 2:1 internal resonance. This interaction strongly affects the dynamics
of the modal response of such resonators. We observe peak splitting, a
signature of energy exchange between the modes even when the modal response is
in the linear regime. We model our device to explain the observed effect of
excitation, detuning of modal frequencies, and intermodal coupling strength on
the resonator dynamics. MoS2 resonators explored in this work are ideal for
understanding the rich dynamics offered through the intermodal coupling.
