Spin-Controlled Integrated Near- and Far-Field Optical Launcher

With the evergrowing demand for miniaturization of photonic devices, the integration of different functionalities in a single module is highly desired for the next generation of ultracompact photonic devices. Optical modules based on the near field and scattered far field are both key elements in the construction of nanophotonic devices. However, integrating the near‐ and far‐field functionalities into a single module is a great challenge, which hinders the integration and minimization of optical devices. Here, a bifunctional integrated near‐ and far‐field optical launcher with a single metasurface structure is theoretically proposed and experimentally demonstrated, where the unidirectional launching of surface plasmon polaritons (SPPs) and the focusing of scattered far fields can be simultaneously achieved. Moreover, the SPP propagating direction and the real/virtual focus of the far‐field scattering can be actively controlled by the spin state of the incident light. With the additional degree of freedom provided by the positions of the metasurface elements, the optical performances of this bifunctional structure can be compared to the one with single functionality. The work provides a new platform for the integration and control of different optical components at subwavelength scale, and opens a way to design multifunctional optical devices for the future.