New York: A team of US researchers has developed a compact, more efficient, complex and secure hologram for better fraud protection. Researchers at the Harvard John A. Paulson School of Engineering and Applied Sciences have programmed polarisation into compact holograms. These holograms use nanostructures that are sensitive to polarisation (the direction in which light vibrates) to produce different images depending on the polarisation of incident light. The results of this advancement, which works across the spectrum of light, improves anti-fraud holograms as well as those used in entertainment displays, was described in journal Sciences Advances. "The novelty in this research is that by using nanotechnology, we have made holograms that are highly efficient, meaning that very little light is lost to create the image," said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering and senior author of the paper. By using incident polarised light, you can see far a crisper image and can store and retrieve more images. Polarisation adds another dimension to holograms that can be used to protect against counterfeiting and in applications like displays," Capasso added. Harvard's Office of Technology Development has filed patents on this and related technologies and is actively pursuing commercial opportunities. "Our holograms work like any other but the image produced depends on the polarisation state of the illuminating light, providing an extra degree of freedom in design for versatile applications," said Mohammadreza Khorasaninejad, first author of the paper and postdoctoral fellow in the Capasso Lab.