Multifunctional photonics: from microwaves to metaoptics
The promise of photonics is to reduce the form factor of common optical components by orders of magnitude by controlling electromagnetic waves in regimes beyond geometrical or physical optics. Many technological applications require a single component that can control multiple wavefronts: metalenses focusing many beams in meta-optics, many-mode converters in photonic integrated circuits, microwave routers and (de-)multiplexers operating at many frequencies. In this talk, I will describe the theory of multifunctional photonics I have been developing as part of the Stone and Miller groups, aimed at answering two fundamental questions: how multifunctional can devices with given material and design constraints be, and how can we design them? I will show how this theory can be applied to two physical systems: compact multifunctional microwave cavities and large-scale free-space-to-photonic-chip mode converters. In the latter case, the theory allowed an order of magnitude improvement in the number of converted modes over designs in the existing literature, promising to enable applications in metrology, optical computing and wavefront shaping.