On-chip metasurfaces unlock efficient vector terahertz beams

An efficient on-chip platform for generating customizable vectorial optical fields is crucial and highly-pursued. While on-chip metasurfaces have opened up avenues for multi-functional coupling from on-chip surface wave to free-space propagating wave, they typically encounter the trade-off between extraction efficiency and wavefront accuracy. Recently, Prof. Lei Zhou’s group pioneered a strategy employing geometric metal meta-atoms with low polarization conversion ratio to overcome this bottleneck and experimentally demonstrated generation of pre-designed terahertz vector beams with efficiency exceeding 90%. This approach establishes a generic, high-performance framework for advanced on-chip meta-devices.