Thermally Reconfigurable Hologram Fabricated by Spatially Modulated Femtosecond Pulses on a Heat-Shrinkable Shape Memory Polymer for Holographic Multiplexing.

Optical security involving the use of light to achieve distinctive vision effects has become a widely used approach for anticounterfeiting. Holographic multiplexing has attracted considerable interest in multiplexing security due to its high degree of freedom for manipulating the optical parameters of incident laser beams. However, the complex and time-consuming fabrication process of metasurface-based holograms and the sophisticated nature of holographic imaging systems have hindered the practical application of holographic multiplexing in anticounterfeiting. Combining holography with shape memory polymers to construct reconfigurable holograms provides a simple and efficient way for holographic multiplexing. This paper proposes a reconfigurable four-level amplitude hologram fabricated on a heat-shrinkable shape memory polymer using spatially modulated femtosecond laser pulses. Simply by triggering the shape recovery of the polymer through heating, the amplitude modulation of light by the hologram is reconfigured through the shrinking of processed microcrater pixels with three diameters, which enables variation to be achieved in reconstructed holographic images. Examples of holographic multiplexing and data encryption are used to validate the proposed method. The proposed economic and simple approach for holographic multiplexing provides an integrated and single-material solution to packaging and optical security, which has extensive potential in anticounterfeiting and optical encryption.