In contrast to conventional optical diffusers usually implemented using thick volume scatterers (exploiting Rayleigh scattering) or microstructured surface scatterers (exploiting geometric scattering), diffusers from dielectric Huygens metasurfaces consist of ultrathin 2D arrays of resonant dielectric nanoparticles. While conventional diffusers can hardly be integrated into chip-scale photonic devices, their metasurface counterpart provides a promising material platform for ultrathin and highly efficient devices. When the nanoparticles of metasurfaces are arranged randomly but statistically specific, diffusers with exceptional properties can be realized. In this contribution, we summarize our recent advances toward dielectric Huygens metasurfaces, which can be used to realize wavelength-selective diffusers with negligible absorption losses and near-Lambertian scattering profiles largely independent of the angle and polarization of the incident waves [1]. Combining a tailored positional disorder with a carefully balanced electrical and magnetic response of the nanoparticles proves to be an integral requirement for operation as diffusers. The directional scattering of the proposed metasurfaces is characterized experimentally and numerically. Their usefulness in wavefront-forming applications is highlighted. Since the metasurfaces are based on the principles of Mie scattering and embedded in a glassy environment, they can be easily integrated into miniaturized photonic devices, fiber optics, or mechanically robust augmented reality displays. Besides the perfect diffusers, we will give an overview of our recent findings on further effects offered by disordered metasurfaces [2,3].

[1] D. Arslan et al., Advanced Materials, 2021, 34, 2105868; [2] A. Rahimzadegan et al., Nanophotonics, 2020, 9, 75-82; [3] A. Rahimzadegan et al., Phys. Rev. Lett., 2019, 122, 015702.