Buckling-induced quadratic nonlinearity in silicon phonon waveguide structures

TL;DR

This paper reports the first observation of quadratic nonlinearity in buckled silicon phonon waveguides, achieved through internal stress and characterized using integrated PZT transducers, enabling control of elastic waves in phononic circuits.

Contribution

It introduces a novel method to induce and control quadratic nonlinearity in silicon phonon waveguides via internal stress and buckling, with experimental validation.

Findings

Observation of softening nonlinear response with drive power

Demonstration of mode shift and frequency conversion

First report of quadratic nonlinearity in buckled phonon waveguides

Abstract

We fabricated and characterized a single-crystal silicon phonon waveguide structure with lead zirconate titanate (PZT) piezoelectric transducers. The compressive stress in a silicon-on-insulator wafer causes a membrane waveguide to buckle, leading to the quadratic nonlinearity. The PZT transducer integrated in an on-chip configuration enables us to excite high-intensity mechanical vibration, which allows the characterization of nonlinear behavior. We observed a softening nonlinear response as a function of the drive power and demonstrated the mode shift and frequency conversion. This is the first report of the nonlinear behavior caused by the quadratic nonlinearity in a buckled phonon waveguide structure. This study provides a method to control the sign and the order of nonlinearity in a phonon waveguide by utilizing the internal stress, which allows the precise manipulation of elastic waves in phononic integrated circuits.