Unveiling Efficient\nAcousto-Optic Modulation in Silicon\nPhotonic Devices via Lithium Niobate Using Transfer Printing

Piezo-optomechanics presents a promising route to convert\nmicrowave\nsignals to the optical domain, implementing processing tasks that\nare challenging using conventional electronics. The surge of integrated\nphotonics facilitates the exploitation of localized light–sound\ninteractions toward new technological paradigms. However, efficient\nacousto-optic interaction has yet to be fully exploited in silicon\ndue to the absence of piezoelectricity, despite its maturity in photonic\nintegrated circuits. Here, we introduce a distinctive acousto-optic\nscheme to supplement silicon photonic devices through heterogeneous\nintegration with lithium niobate (LN). Utilizing LN as an efficient\nacoustic pump to harness the inherently exceptional photoelasticity\nin silicon, we demonstrate efficient microwave-to-acoustic transduction,\nultimately achieving a modulation figure-of-merit of <i>V</i><sub>π</sub><i>L</i> ∼ 0.496 V·cm. This\nefficient modulation scheme is further extended to implement non-reciprocal\nintermodal modulation. The proposed hybrid integration route opens\nnew possibilities for tailoring photon–phonon interactions\nin silicon, consolidating acousto-optic technology in multifunctional\nintegrated photonics.