  Highly efficient acousto-optic modulation plays a vital role in the
microwave-to-optical conversion. Herein, we demonstrate a hybrid thin-film
lithium niobate (TFLN) racetrack micro-ring acousto-optic modulator (AOM)
implemented with low-loss chalcogenide (ChG) waveguide. By engineering the
electrode configuration of the interdigital transducer, the double-arm
micro-ring acousto-optic modulation is experimentally confirmed in nonsuspended
ChG loaded TFLN waveguide platform. Varying the position of blue-detuned bias
point, the half-wave-voltage-length product VpaiL of the hybrid TFLN micro-ring
AOM is as small as 9 mVcm. Accordingly, the acousto-optic coupling strength is
estimated to be 0.48 Hz s1/2 at acoustic frequency of 0.84 GHz. By analyzing
the generation of phonon number from the piezoelectric transducer, the
microwave-to-optical conversion efficiency is calculated to be 0.05%,
approximately one order of magnitude larger than that of the state-of-the-art
suspended counterpart. Efficient microwave-to-optical conversion thus provides
new opportunities for low-power-consumption quantum information transduction
using the TFLN-ChG hybrid piezo-optomechanical devices.
