Extreme decoupling in dense high quality factor phase gradient metasurfaces

High Q phase gradient metasurfaces are promising candidates for enhancing wavefront shaping and nonlinear technologies but near-field coupling typically forces a trade-off between quality factor and spatial resolution. Here, we show that polarization-based interference can be used to eliminate the trade-off between quality factor and spatial resolution. To show the power of our platform, we simulate high angle beam-splitting (±53o) and beam-steering (33o) with diffraction efficiencies over 90% with index modulation as small as 2×10^-6 and subwavelength pitch of λ/1.6. To experimentally verify our approach, we show that by geometrically sweeping our metasurfaces we can triangulate a decoupling configuration. Also, we show that angle dispersion another symptom of nearfield coupling can be fully suppressed. Our demonstrated platform paves the way for dynamic high-resolution wave-shaping applications requiring small modulation depth.