Reconfigurable terahertz beam splitters enabled by inverse-designed meta-devices

The beam splitter is one of the most crucial components in optical and electromagnetic systems, and it is also expected to be applied in terahertz (THz) technology. However, most existing beam splitters operate in only a single working mode, restricting their applications. This paper reports a method for the inverse design of a doublet meta-device consisting of two stacked metasurfaces functioning as a reconfigurable THz beam splitter. It is made of photo-curable high-temperature resin using 3D printing technology. By simply adjusting the relative rotation angles between the two metasurfaces to 0°, 90°, 180°, and 270°, the meta-device can produce four distinct focal patterns, thus achieving four different working modes. This scheme avoids introducing complicated active components, offering a simple, low-cost design of a signal divider in future 6G THz communication systems.