UC Santa Barbara

Phased-array metasurfaces offer a wide design space to arbitrarily shape the wavefront of light. As such, metasurfaces have been used to create various miniature and light-weight optical components such as lenses and beam steerers with applications ranging from augmented reality to space flight and LiDAR. Metasurface optical elements typically transform a well-defined incident light beam into a desired output waveform. Luminescent emission, on the other hand, is not well-defined in either space or momentum. Thus, light emitting metasurfaces offer intriguing opportunities to study fundamental light-matter interactions and further miniaturize optical components. To date, most luminescent metasurfaces have been uniform arrays of scatterers and are therefore unable to provide granular control over the wavefront of emitted light. Recent work demonstrating wavefront control of spontaneous emission using phased-array metasurfaces, on the other hand, suffer low efficiency and peculiar polarization dependencies. In this work, we develop and verify a reciprocal simulation strategy to explain the polarization disparity and improve unidirectional emission efficiency of phased-array metasurfaces. We then use these reciprocal simulations to design metasurfaces to steer light from systems where emission originates from alternate quantum mechanical processes. Additionally, we pair these reciprocal simulations with Bayesian optimization to facilitate the design of highly unidirectional photoluminescent metasurfaces capable of directive p-, s-, or combined p- and s- polarized emission at arbitrary angles. Our inverse design approach enables 54% improvement in directivity and the first-ever simultaneous directional emission of s- and p-polarized light. We expand the optimization tools developed for light emitting metasurface and apply them to quantum optics. Magneto-optical atomic traps are a critical part of modern science, but future applications in gravity mapping and space-based atomic clocks require smaller, more robust traps. We design a metasurface retroreflector to replace two bulk optical components and eventually reduce trap volume by three orders of magnitude. The metasurface is designed for polarization insensitive retroreflection of 780 nm circularly polarized light at 54.7°. The proof-of-concept device retroreflects circularly polarized 736 nm light at 50.3°. We discuss oxidation mitigation strategies for future devices and propose a corrective optic for the currently fabricated device. With a better understanding of light-matter interactions and sophisticated modeling and optimization tools, this work represents a step toward smaller, more efficient devices. Full control over the polarization and momentum of light emitted by incoherent sources will lead to lighter, more energy efficient displays whereas the miniaturization of magneto-optical traps will allow the expansion of cold-atom science beyond the laboratory.