Randomly Induced Phase Transformation in Silk Protein-Based Microlaser Arrays for Anticounterfeiting

Anticounterfeiting labels based on physical unclonable functions (PUFs) exhibit high security with unreplicable code outputs, making them an ideal platform to realize unbreakable anticounterfeiting. Although various schemes are proposed for PUF labels, the utilization of natural randomness suffers from unpredictable signal extraction sites, which poses a challenge to efficient and convenient authentication for practical anticounterfeiting applications. Here, a covert optical PUF-based cryptographic protocol from silk protein-based microlaser (SML) arrays that possess hidden randomness of lasers for unclonable lasing signals as well as a defined location for efficient identification is proposed. The initial SMLs are patterned by casting laser dye-doped regenerated silk fibroin solution, resulting in a uniform microlaser array with regulated positions. With the SML array as substrate, random methanol microdroplets are stochastically sprayed on the SML array, which eventually induces uneven lasing signal changes of the patterned microlasers. The treated SML array possesses the deterministic readout sites of laser signals and unrepeatable signal distribution characteristics, which can guarantee efficient authentication and high security when serving as an anticounterfeiting label.