A Toolkit for Multiscale Optical System Inverse-Design

Optical system design is undergoing a transformational change with the increases in computational horsepower, cuttingedge algorithmic developments, and the advent of new nanofabrication technologies. Among the most exciting advances in recent memory are optical metasurfaces, which are patterned surfaces commonly realized through nanofabrication that can imbue optical engineers with expanded degrees of design freedom due to their ability to exploit the generalized form of Snell's law. Through intelligent optimization and design, metasurfaces can be constructed which achieve arbitrary chromatic dispersion behaviors and unprecedented control over polarization that simply cannot be realized with conventional optical elements. However, designing high-performance metasurfaces requires the use of full-wave simulation tools and numerical optimization techniques which necessitate considerable computational resources. Moreover, while optical metasurfaces are moving towards millimeter and centimeter scale diameter lenses with advances in nanofabrication techniques, it is computationally infeasible to employ full-wave simulation tools directly to model optical systems that use such large size elements. Nevertheless, the size, weight, and power (SWaP) advantages afforded by optical metasurfaces make them a compelling choice for designers to consider in a number of applications, which are currently limited by bulky conventional optical solutions. Therefore, techniques that can rapidly model metasurfaces in conjunction with conventional optical elements such as lenses, mirrors, and prisms are highly desirable. In this presentation, we highlight a toolkit of custom solvers, design procedures, and powerful optimization algorithms that simplify and accelerate the development of hybrid optical systems with arbitrary combinations of conventional and metasurface elements.