Electro-Acoustic Phase Modulator Based on AlScN Thin Film

Acoustic waveguides and ring resonators based phononic integrated circuits (PnIC) have attracted more and more attention due to potential applications in the quantum system and signal processing. However, there are very few studies on active modulation utilizing electro-acoustic (EA) effect. PnIC requires efficient modulation components as well as a high electromechanical coupling platform. Here we demonstrate an acoustic wave phase modulator based on AlScN thin film. The acoustic wave phase of proposed AlScN thin film devices can be controlled through the driving voltage, modulation length as well as the acoustic wavelength. A
$\pi $
phase shift is obtained at an amplitude of 62.5 V DC bias on an acoustic waveguide of
$100~\mu \text{m}$
long at the acoustic wave of approximately 1.975 GHz, i.e.,
$\text{V}\pi \cdot \text{L}$
=
$6.25^{\ast} 10^{-3}\,\,\text{V}\cdot \text{m}$
. Moreover, acoustic frequency combs and serrodyne frequency translators have been demonstrated. Such high performance AlScN thin film EA phase modulator proves a new PnIC platform for future hybrid chip-scale phonon transduction and signal processing.