Optical metasurfaces have developed as a breakthrough concept for advanced wave‐front engineering enabled by subwavelength resonant nanostructures. However, reflection and/or absorption losses as well as low polarization‐conversion efficiencies pose a fundamental obstacle for achieving high transmission efficiencies that are required for practical applications. Here, for the first time to our knowledge, highly efficient all‐dielectric metasurfaces are demonstrated for NIR frequencies using arrays of silicon nanodi…