In this paper we experimentally evaluate a physical unclonable function based on a polymer optical waveguide, as a time-invariant, replication-resilient, source of entropy. The elevated physical unclonability of our implementation is combined with spatial light modulation and post processing techniques, thus allowing the deterministic generation of an exponentially large pool of unpredictable responses. The quality of the generated numbers is validated through NIST/DIEHARD(ER) suites, whereas the overall security of the scheme is benchmarked assuming attackers with elevated privileges in terms of system access. Finally, based on the demonstrated key features, we present and analyze a mutual authentication implementation scenario which is fully compatible with state-of-the-art commercial Internet-Of-Things architectures