stored IXs can be reconverted to photons by selecting an appropriate source voltage to reduce the IX recombination lifetime. The EXAT source acts, therefore, as a voltage-tunable location for photon-to-exciton interconversion as well as for IX storage.

![(a) Top view of the acoustic exciton multiplexer (EXAM): each I/O area contains an exciton optoelectronic transistor (EXAT) and an IDT for SAW generation (not shown). The vertical (horizontal) dotted rectangle delineates the transport channel formed by SAW$_1$ (SAW$_2$ or SAW$_3$) underneath the common drain. The dashed arrows indicate IX transfer between SAW$_1$, SAW$_2$ and SAW$_3$. The solid square labeled *I* denotes the intersection region of SAW$_1$ and SAW$_2$ (or SAW$_1$ and SAW$_3$). (b) Array of moving potential dots formed by SAW interference at *I*. (c) Simulated time-averaged emission pattern within *I* showing the IX transfer between SAW$_1$ and SAW$_2$.[]{data-label="Fig2"}](Figure_3.png){width="\columnwidth"}

IX transfer between two facing I/O ports (e.g., ports 1 and 4 in Fig. \[Fig2\](a)) is carried out by simply turning the corresponding SAW and EXAT (i.e., SAW$_1$ and EXAT$_1$) ON. The multiplexing function relies on the transfer of IXs between two orthogonal acoustic beams (e.g., from the vertical beam SAW$_1$ to the horizontal beam SAW$_2$ or SAW$_3$) at their intersection area (*I* 