High-CapacityMultilayeredLuminescent EncryptionTechnology Based on Er-Implanted Silicon Treated by Pulsed Laser Annealing

Luminescent encrypted labels can effectively solve the problem of counterfeiting. However, they suffer from complex design and fabrication, low space utilization, and limited capacity of encrypted information. Herein, we create multilayer infrared luminescent encryption labels using femtosecond-laser-activated Er-doped silicon. In comparison with other annealing techniques that treat the whole sample at once, femtosecond lasers have a high spatial precision and flexibility, which can locally anneal the Er-doped Si, generating stable and controllable multilayered photoluminescent patterns. It therefore can significantly enhance security and increase the information storage capacity. This work demonstrates a low-cost, high-capacity, and high-security encrypted label with great application value. Fs-laser-annealed Er-doped silicon is also a promising material to realize quantum light sources or gain materials for lasers at the communication band.