Light transport through ultrafast chaotic micro-cavities for photonic physical unclonable functions

We present a comprehensive ray tracing analysis of a novel photonic physical unclonable function (PUF) based upon the ultrafast nonlinear optical interactions in a silicon chaotic micro-cavity exploited for secure authentication and communication. The cavity's design exhibits complex chaotic behavior that ensures extreme sensitivity to the precise physical structure made unique through fabrication variances. As such, the PUF's security is partly ensured by the extreme difficultly faced in simulating a cavity's response with significant accuracy. However, general behavior from simulations can guide the design process to, for example, maximize response unpredictability and enhance interaction complexity. Although computational electrodynamic methods which solve Maxwell's equations are prevalent, they have high processing costs which negate rapid design optimization. Here we show the results of a ray tracing analysis to quantify the chaotic nature of the device and examine the subsequent impact of fabrication variance. We further compare these results to finite element simulations and experimental results to examine accuracy. This computationally-efficient method can serve as a valuable tool in the development of these next-generation security devices.