OP: Investigating High-K Modes in Metamaterial Structures

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Nontechnical description: This project addresses the properties of metamaterials - layered structures comprising alternating thin films of electrically conducting and insulating materials. The optical characteristics of these metamaterials depend on the properties of the conductor and the insulator, as well as the structural details of the layers. Metamaterials alter the normal propagation of light, enabling effects like imaging of objects much smaller than the wavelength and backwards bending of light. The overarching goal of this project is to better understand such effects and how they may be harnessed in novel applications. First, the research team is investigating how these metamaterials may be used to focus light into ultra small spots, to enable intense light concentration. Second, light absorbing materials are being placed inside the metamaterial to understand how the unusual light propagation alters their properties. Such structures may enable efficient sensors for environmental gas monitoring. During the summer months, female undergraduate students and a high school intern work together with the research group, to help broaden the participation of underrepresented groups in science. This research is also being used to develop a science education module, to be made available to the local community at various outreach events.Technical description: The goal of this project is to understand and control light propagation through infrared hyperbolic metamaterials (HMMs). These HMMs comprise alternating layers of doped and undoped semiconductors grown by molecular beam epitaxy. This method enables the growth of crystalline HMMs with low losses, sharp interfaces, high lateral uniformity, tunable optical properties, and atomic control over layer thickness. Light transmission through subwavelength gratings is the first topic of investigation. Near-field imaging is used to examine extreme subwavelength focusing and imaging of subwavelength features. The second topic aims to incorporate quantum wells into the HMM structure. This enables modulation of the overall optical properties of the structure via strong coupling between the quantum well intersubband transition and the HMM optical states. This research develops the fundamental understanding required for the creation of monolithically integrated infrared optical systems based on designer semiconductor HMMs.