Photo-Transformable Gratings for Augmented Reality

The seamless integration of multiple diffractive optical elements (DOEs) into a single-level substrate has been the key for the advancements in augmented reality (AR) technologies. Presently, serial-type lithographic manipulations such as electron-beam lithography can successfully provide a deterministic route toward this end. The large-scale utilization of these processes, however, is impractical owing to their high cost. The holographic inscription of photochromic materials can offer an etching-free and wide-scale strategy for the cost-effective development of large-area 1D DOEs. Given the processing time, the accessible DOE area from this holographic inscription is more than several orders of magnitude larger (10⁸–10¹⁰ µm² h⁻¹) than that obtained through the aforementioned lithography (10²–10⁵ µm² h⁻¹). However, erasing, which is believed to be prevalent in the multiscale integration of various DOEs, deteriorates the pattern integrity and throughput. Here, it is proposed that the technical conundrum resulting from erasing and re-inscribing the DOEs can be effectively circumvented by transforming the already formed DOEs without erasing. Centimeter-scale mosaic DOEs can be readily developed within an hour, which in turn facilitate advanced AR demonstrations. This approach leverages the ability of holographic inscription to seamlessly integrate the wide-scale multiple DOEs as well as their utility as a go-to tool for AR technologies.