Light field manipulation using micrometer-scale diffractive surfaces fabricated by two-photon nanolithography

The manipulation of light at the micrometer scale has been the core technology for the recent development of diffractive optics, especially for optical displays and diffractive neural networks (NNs). However, the factors that influence the diffraction efficiency of the diffractive surfaces have not been well understood. Taking advantage of a simplified physics-driven neural network model and two-photon nanolithography (TPN) technology, we theoretically and experimentally investigated the factors that influence the diffraction efficiency of the diffractive surfaces, such as diffraction propagation distances and a variety of diffraction patterns with different geometrical features, the result of which enables the generation of two-dimensional images with high diffraction efficiencies through the diffractive surfaces with a thickness of less than 1 μm and a size of 100 μm by 100 μm. The demonstrated results are of great significance for optical light manipulation in optical display and computational imaging using free-space diffractive optical elements.