Freely manipulating on-chip sources by intelligent-algorithm vectorial metasurfaces based on an identity scheme

Metasurfaces have exhibited huge potential for manipulating fields of both free-space and on-chip light sources. To design a metasurface, a group of nano-scatterers should be firstly found and optimized and then be arranged. For on-chip integrated light sources, the scattering amplitudes, phases, and polarizations of nano-scatterers depend on not only incident directions of light but also in-plane orientations of nano-scatterers. This greatly increases the difficulty of designing metasurfaces for freely manipulating fields of on-chip light sources, such as achieving multiple emission directions (even with complex emission patterns) with fully independent polarization states. Herein, we propose to utilize an identity scheme, which employs identical nano-scatterers with only one incident angle, to eliminate the harmful influence of diverse incident directions of light and in-plane orientations of nano-scatterers on scattering properties of nano-scatterers. So, it is not needed any more to seek nano-scatterer groups for on-chip light sources. Then, a self-discretized iterative computational holographic intelligent algorithm is exploited to arrange these identical nano-scatterers to create vectorial metasurfaces, enabling free manipulation of on-chip light sources. Multiple (up to 8) collimated emission beams (divergence angles ≤ 1.4°) with fully independent polarization states of high purities are demonstrated. Moreover, complex emission patterns with different emission directions and different polarization states are also presented experimentally. This identity scheme and the intelligent algorithm provide new perspectives for designing metasurfaces, especially for freely manipulating on-chip sources.