Phononic Frequency Combs in Beam Structures

Summary— Phononic frequency combs are the acoustical equivalents of the photonic frequency combs. The photonic frequency combs have many current uses [1]. The phononic frequency combs on the other hand are new, but potentially we might find useful applications for them in RF devices [2]. Currently, the phononic frequency combs are generated by resonating structures that have two or more modes of vibrations in close frequency proximity, or in certain frequency ratios for parametric excitation, so that the modes could interact nonlinearly. Researchers would try to design piezoelectric structures carefully so that the modes could interact nonlinearly in terms of material nonlinearity, geometric nonlinearity and damping.This work shows that the phononic frequency combs could be generated in beam structures without the need to design the structures to have modes in close frequency proximity, and without material nonlinearity. The frequency combs could be modelled using the Von Karman beam equations.