Thermo-acoustic Phase Modulator based on Y36-cut LiNbO₃ Thin Film

Microwave acoustic components have higher quality factors and less crosstalk than electromagnetic components. Efficient modulation of acoustic devices is essential for building large-scale multifunctional acoustic circuits. Here, we demonstrate a thermo-acoustic phase modulator based on a Y36-cut LiNbO<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</inf> (LN) thin-film platform. The proposed structure integrates a 460 MHz SH<inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</inf> mode acoustic delay line (ADL) with an on-chip microheater for locally changing the temperature and thus controlling the phase of the ADL. Using this approach, we achieve a phase change of more than 281° at a heating power of 20 mW, and a modulation ability of 17 °/mW in the linear modulation range, which is 6.5 times improvement over previously reported bulk-LN platforms. Our thermo-acoustic modulators enable reconfigurable acoustic signal processing for next-generation wireless communication and microwave systems.