Speaker:  Pengning Chao  (MIT)

Title:  A general frameword for computing fundamental limits in photonics inverse design

Abstract:

Advances in computing power and numerical algorithms has lead to a paradigm shift in photonics engineering towards inverse design: achieving desired functional characteristics by solving a PDE-constrained optimization problem over a large number of structural parameters. This approach has been very fruitful, with increases in device performance often measured by orders of magnitude. However, the resulting structures can be highly complex, and a natural question is to what extent further improvement is possible. Unfortunately, the high-dimensional, non-convex nature of the PDE-constrained optimization precludes the exact determination of its global optimum.  To address this issue, this talk presents a general framework for computing fundamental limits to photonics device performance based on a systematic convex relaxation of the original optimization. The efficacy of the framework is demonstrated on canonical problems such as maximizing scattering cross-sections and manipulating the photonic local density of states. Further extensions and improvements will also be discussed. Based on joint work with the groups of Sean Molesky and Alejandro Rodriguez.