Broadband Holography via Structured Black Silicon Nano-Antennas

Computer-generated holograms have wide applications in different fields of optics, ranging from imaging, to data storage and security.

Current holograms have limited bandwidth and are generated via nanofabrication techniques that are difficult to scale up and in some cases require the use of expensive metallic media.

Here we report a new single-step technique for the fabrication of large-scale computer-generated holograms from an inexpensive material, such as Silicon. Our approach exploits dry etching to create a series of broadband nanoantennas, which can tune the reflectivity of Si from an average of 0.35 to 0.1 in the entire visible range. We demonstrated the realisation of different images at wavelengths of 450 nm, 532 nm, and 632 nm with an efficiency of 10%, 14%, and 12%, respectively. This scalable approach opens up application of large-scale broadband computer-generated holographic surfaces for many different applications.

Read more at: Appl. Sci. 2019, 9(7), 1378