Topology Optimization of Nonlinear and Meta-Photonic Devices

Abstract

Recent years have witnessed an exciting quest for exotic materials and unusual states of matter involving enhanced optical, mechanical, and quantum properties. However, there has been comparatively less effort devoted to discovering unconven- tional structures that can enhance the functionality of ordinary materials, such as ubiquitous low-loss isotropic dielectrics. This thesis represents an effort to leverage the capabilities of large-scale computational methods, known as topology opti- mization or inverse design, to uncover novel geometries and enhanced physical properties that can be realized in simple dielectrics. In particular, we address three diverse areas in photonics to demonstrate the versatility and power of inverse design. Firstly, we present topology-optimized structures with finely tailored resonances for maximizing the efficiencies of nonlinear optical processes by orders of magnitude. Secondly, we design exotic spectral features, known as Dirac cones and exceptional points, with the possibility of greatly enhancing radiative powers from optical emit- ters. Thirdly, we propose multi-layered meta-optical devices with angular phase control that allow, among others, the design of an ultra-thin single-piece metalens with multiple aberration corrections.