Demonstration of acousto-optic modulation using an integrated Michelson interferometer

Integrated photonic acousto-optic (AO) modulators have emerged as critical components across diverse fields ranging from classical optical manipulation to quantum information processing. Here, by using a lithium niobate-chalcogenide heterogeneous integration platform, an integrated AO modulator based on an on-chip Michelson interferometer is demonstrated for the first time. A serpentine waveguide configuration is further incorporated to allow continuous propagation of surface acoustic waves through triple-folded waveguide segments, and the modulation efficiency is significantly enhanced by 7.3 dB through the extension of the effective AO interaction length and the utilization of bidirectional acoustic energy. Experimental results confirm an improvement in modulation efficiency to -18.8 dB at 15 dBm radio frequency power, while achieving a low half-wave voltage-length product of 0.02 V·cm. This research represents a significant stride forward in integrated AO modulation, providing new opportunities for microwave-to-optical conversion systems.