Developing Multi-Modal Anti-Counterfeiting Systems with Randomized Whispering Gallery Mode Active Microresonators

Abstract Counterfeiting presents critical global challenges, demanding advanced anti-counterfeiting technologies. This study introduces a scalable optical physically unclonable function (PUF) system based on whispering-gallery mode (WGM) resonators formed by polystyrene microspheres coated with AgInS 2 /ZnS quantum dots (QDs). The system leverages geometric variations in microspheres’ features to generate unique spectral signatures for secure optical identifiers. While the fabrication process allows control over the average size of the microspheres and the emission band of the QDs, the precise positions and quality factors of the WGM resonances remain inherently stochastic due to geometric variations in the microspheres. The scalable and cost-effective layer-by-layer deposition method ensures industrial feasibility while supporting diverse applications. This system integrates controlled and stochastic factors into a multiparametric design, enhancing the complexity and security of the identifiers. By addressing scalability and adaptability challenges, this work demonstrates the potential of WGM-based PUF systems for robust, versatile, and next-generation anti-counterfeiting applications.