Tunable color generation in CdTe-doped silicate glass enabled by ultrashort laser pulses: interior coloring and multilevel encryption

The launch of the big data era puts forward challenges for information security. Herein, a new kind of silicate glass system co-doped with CdO and ZnTe, capable of achieving the controllable generation of intrinsic color centers (brown and green) and tiny nuclei of CdTe via direct laser writing (DLW), is developed. The controlled growth of CdTe QDs thermally, leads to a permanent color of orange at the cost of accelerated aging of the color centers of brown and green. On the one hand, going beyond traditional 2D surface coloration, the high transparency of the studied bulk medium makes 3D volumetric interior coloration possible. On the other hand, by encoding ciphertext into the tiny nuclei of CdTe, a strategy of color encryption and heat decryption is established, which brings about the merits of expanded storage capacity and improved information security. The demonstration application confirmed the user-defined multiscale interior coloration and an unprecedented multidimensional color-encryption scheme with a high-security level. The present work highlights a great leap in transparent materials for color encryption and hopefully stimulates the development of new color division multiplexing encryptions. (C) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement