Metamaterial Super Absorber for Light-Matter Interaction: from Broadband to Extreme Field Confinement

摘要

Metamaterial is a new class of artificially structured media exhibiting exotic properties that do not exist in conventional materials. In recent decades, the investigation of light-matter interactions with metamaterials have become an intense area of research in the field of photonics. The engineered response of metamaterials can be designed to exhibit strong coupling with the electric and/or magnetic component of an incident electromagnetic wave by tailoring the shape, size, lattice constant, interatomic interaction of the "atoms".;Light absorption, which is one of the most fundamental light-matter interaction, is an essential phenomenon in a variety of the optical application, such as photovoltaics and thermal management. Therefore, a particular branch---the metamaterial super absorber---has garnered interest due to the fact that it can achieve angle- and polarization-insensitive and near unity absorptivity of electromagnetic waves.;This thesis is largely focused on the development of plasmonic metamaterial super absorber for light-matter interaction from two aspects: 1. Increasing the absorption band for broadband application, e.g. on-chip thermal management, radiative cooling, and thermal photovoltaics; 2. Maximize the electric field generated by the magnetic resonance, for extremely sensitive sensing applications.;In chapter 2, I will discuss a novel platform---hyperbolic metamaterial (HMM)---for broadband plasmonic metamaterial super absorber. By properly designing the geometric parameters of the structures, the on-chip broadband super absorber structure based on HMM waveguide taper array with strong and tunable absorption profile from NIR to mid-infrared (MIR) spectral region can be realized.;In chapter 3, the plasmonic metamaterial super absorber will be combined with nanometric gaps to maximize the localized field by squeezing EM waves into sub-5nm-gaps. Optical field can be concentrated into deep-subwavelength volumes and realize significant localized-field enhancement (so called "hot spot") using metallic nanostructures.;In chapter 4, the structures investigated in chapter 3 is used to design a novel surface enhanced sensing platform. Such a novel metamaterial super absorber substrate represents a record for surface enhanced infrared absorption spectroscopy.