Holographic polymer nanocomposites with simultaneously boosted diffraction efficiency and upconversion photoluminescence

Abstract

Holographic polymer nanocomposites have drawn considerable attention due to their unique capability of reconstructing colored three-dimensional (3D) images identifiable to the naked-eye. Yet, it still remains challenging to add more and orthogonal (i.e., data access without crosstalk) optical functions to current holographic polymer nanocomposites. Herein, we design and demonstrate a holographic polymer nanocomposite with robust optical diffraction and upconversion photoluminescence. This paradigm is enabled by controlling the spatial location of upconversion nanorods (UCNRs) in the constructive (polymer-rich) regions during holographic recording, while utilizing the phase separating liquid crystal (LC) in the destructive regions to boost the refractive index difference between the constructive and destructive regions. One identical holographic image is reconstructed and readily visible to the naked-eye under ambient light, whereas four different covert luminescence states (i.e., none, blue, yellowish green and red emissions, respectively) can only be distinguishable upon the 980 nm laser illumination. The double-verifiable and crosstalk-free optical features pave a way to design new tags with orthogonal optical functions for anti-counterfeiting and security applications.