Polarization mode hybridization and conversion in phononic wire waveguides

Abstract

Phononic wire waveguides of subwavelength cross-section support two orthogonal polarization modes: the out-of-plane motion dominated Rayleigh-like and the in-plane motion dominated Love-like modes, analogous to transverse-electric and transverse-magnetic modes in photonic waveguides. Due to the anisotropic elasticity of the substrate material, the polarization states of phonons propagating along certain crystallographic orientations can strongly hybridize. Here we experimentally investigate the orientation-dependent mode hybridization in phononic wire waveguides patterned from GaN-on-sapphire thin films. Such mode hybridization allows efficient actuation of piezoelectrically inactive Love-like modes using common interdigital electrodes designed for Rayleigh-like modes, and further enables on-chip polarization conversion between guided transverse modes. Both are important for on-chip implementation of complex phononic circuits.

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Cited by in corpus (3)

• High-acoustic-index-contrast phononic circuits: numerical modeling
• Adiabatic conversion between gigahertz quasi-Rayleigh and quasi-Love modes for phononic integrated circuits
• Buckling-induced quadratic nonlinearity in silicon phonon waveguide structures