Internal resonance between transverse vibration modes of a 2D material nanostrip under laser opto-thermal excitation

In this work, the nonlinear dynamics of opto-thermally excited oscillations of a nanostrip made of a two-dimensional material is studied. Based on geometrically nonlinear equations of coupled longitudinal-transverse vibrations, the internal resonance scenario mechanically inherent to the system between two transverse natural modes with a frequency ratio of 1:2 is considered. The features of the dynamics of a nanoresonator are studied under conditions of the primary parametric resonance in the lowest mode of vibration and the combined primary external and secondary parametric resonance in the highest mode. A significant difference in the structure of possible stationary modes of nanoband oscillations under conditions of resonant intermodal interaction from the classical picture typical of a parametrically excited nonlinear oscillator is demonstrated. The effect of vibration damping in the higher mode of a nanostrip due to the exchange of energy between excited forms is discussed. It is shown that taking into account the nonlinear coupling of modes makes it possible to detect strong modal localization of oscillations in the system in a certain frequency range of laser action.