Optical metasurface refers to a kind of nanostructured material with sub-wavelength thickness and on-demand optical properties, which are not possible for natural materials. By rationally engineering the metasurface structures, one could achieve new capabilities for the manipulation of light, e.g., ultra-thin flat lenses, waveplates and holographic plates. Yet, the optical efficiency and performance of most metasurface-based devices are yet to improve to meet the requirements for real-world applications. In this talk, I will present our research on highly efficient on-chip integratable metasurface devices for ultra-compact polarimetric detection and imaging devices.
I will discuss about our approach to realize highly efficient broadband hybrid metasurfaces (based on integrated dielectric and plasmonic metasurfaces) for phase and polarization control of light in near infrared wavelength (1.2-1.7 µm). We have theoretically investigated and experimentally demonstrated circular polarization (CP) detection with CP extinction ratio (defined as the ratio between the transmission of CP light with desired handedness and that of CP light with the other handedness) of 30 and transmission efficiency over 80%.
I will also discuss about another approach of realizing highly efficient plasmonic metasurfaces for phase and polarization control of light in mid-infrared wavelength (2-12 µm). Despite the high ohmic loss of plasmonic metasurfaces, I will show that by rationally designing the metasurface structure, it is possible to realize highly efficient plasmonic devices with superior performance. As a proof-of-concept demonstration, we have designed and experimentally demonstrated CP polarization filters with transmission efficiency >85% and CP extinction ratio >50 at 4 µm (bandwidth > 600 nm for CP extinction ratio> 10). The total thickness of the metasurface structure is less than 1/10 of the operational wavelength.
Last but not the least, I will present our recent progress on chip-integration of metasurface devices for full-stokes polarimetric detection and imaging.