Nonlinear Light-Matter Interactions in Metamaterials
Metamaterials possess extraordinary linear optical properties never observed in natural materials such as a negative refractive index, enabling exciting applications such as super resolution imaging and cloaking. In this thesis, we explore the equally extraordinary nonlinear properties of metamaterials. Nonlinear optics, the study of light-matter interactions where the optical fields are strong enough to change material properties, has fundamental importance to physics, chemistry, and material science as a non-destructive probe of material properties and has important technological applications such as entangled photon generation and frequency conversion. Due to their ability to manipulate both linear and nonlinear light matter interactions through sub-wavelength structuring, metamaterials are a promising direction for both fundamental and applied nonlinear optics research.
We perform the first experiments on nonlinear propagation in bulk zero and negative index optical metamaterials and demonstrate that a zero index material can phase match four wave mixing processes in ways not possible in finite index materials. In addition, we demonstrate the ability of nonlinear scattering theory to describe the geometry dependence of second and third harmonic generation in plasmonic nanostructures. As an application of nonlinear metamaterials, we propose a phase matching technique called "resonant phase matching" to increase the gain and bandwidth of Josephson junction traveling wave parametric amplifers. With collaborators, we demonstrate a best in class amplifier for superconducting qubit readout - over 20 dB gain with near quantum limited noise performance with a bandwidth and dynamic range an order of magnitude larger than alternative devices. In conclusion, we have demonstrated several ways in which nonlinear metamaterials surpass their natural counterparts. We look forward to the future of the field where nonlinear and quantum metamaterials will enable further new physics and new applications.