Atomic-Probe-Controlled Hydrogenation for Configurable Flat Optics

The development of active nanophotonics demands configurable materials with high spatial resolution. Here, we demonstrate the direct fabrication of a flat optical diffraction grating utilizing a lithography-free, probe-based nanoscale patterning strategy. Specifically, local hydrogen ion injection via a Pt-coated atomic force microscopic probe triggers a seven-order-of-magnitude resistivity rise and a 12.6% out-of-plane lattice expansion in NdNiO3 film, dynamically transforming the nano- or microscale area from an opaque metal into a transparent insulator. Alongside this extremely different optical contrast, the tip-induced process features a deep subwavelength spatial resolution of ∼100 nm, with a low operational threshold voltage of ∼1.1 V, and continuous grayscale programmability. By leveraging this distinct optical contrast and high spatial fidelity, we successfully fabricate and optically validate a microdiffraction grating and holographic diffraction. This work establishes atomic-probe-controlled hydrogen injection as a powerful, energy-efficient paradigm for prototyping programmable diffractive optical elements and next-generation flat optics.