This paper presents the development of all-silicon multidimensionally-encoded optical physical unclonable functions (PUFs) for integrated circuit anti-counterfeiting in IoT devices. The PUFs are fabricated using a CMOS-compatible process, integrating a silicon metasurface and erbium-doped silicon quantum dots (Er-Si QDs). These PUFs generate five in-situ optical responses within a single pixel, achieving an ultrahigh information entropy of 2.32 bits/pixel. The position-dependent optical responses are attributed to the radiation field and Purcell effect, resulting in unique fingerprints for each PUF. The performance of the PUFs is evaluated through various metrics, including bit uniformity, similarity, intra- and inter-Hamming distances, false-acceptance and rejection rates, and encoding capacity. The PUFs demonstrate excellent anti-counterfeiting capabilities and are further utilized to implement efficient lightweight mutual authentication protocols for IoT applications. The scalability, cost-effectiveness, and robustness of the fabrication process make these PUFs suitable for large-scale production and practical deployment in IoT systems.This paper presents the development of all-silicon multidimensionally-encoded optical physical unclonable functions (PUFs) for integrated circuit anti-counterfeiting in IoT devices. The PUFs are fabricated using a CMOS-compatible process, integrating a silicon metasurface and erbium-doped silicon quantum dots (Er-Si QDs). These PUFs generate five in-situ optical responses within a single pixel, achieving an ultrahigh information entropy of 2.32 bits/pixel. The position-dependent optical responses are attributed to the radiation field and Purcell effect, resulting in unique fingerprints for each PUF. The performance of the PUFs is evaluated through various metrics, including bit uniformity, similarity, intra- and inter-Hamming distances, false-acceptance and rejection rates, and encoding capacity. The PUFs demonstrate excellent anti-counterfeiting capabilities and are further utilized to implement efficient lightweight mutual authentication protocols for IoT applications. The scalability, cost-effectiveness, and robustness of the fabrication process make these PUFs suitable for large-scale production and practical deployment in IoT systems.