Uniform 2D Target Generation via Inverse-designed Metasurfaces.

We propose an inverse design framework for metasurfaces that achieves highly uniform two-dimensional intensity profiles across an on-demand shape. The optimization objective is formulated to enhance overall projection efficiency via the adjoint method, while a regularization term penalizes local deviations in field amplitude to suppress intensity non-uniformity. The regularization weight is adaptively tuned based on the current non-uniformity, enabling stable and efficient optimization. Compared with the widely used mean squared error (MSE) objective, our method yields superior performance in both intensity fidelity and uniformity. We also extend our framework to handle realistic Gaussian beam illumination by biasing the library. This framework utilizes the Finite Element Method (FEM) for surrogate modeling and full-wave Finite-Difference Time-Domain (FDTD) simulations for rigorous verification. Simulation results confirm the effectiveness of our approach for generating high-quality, uniform field patterns.