Design and Manufacturing of Polarization Beam-Splitting Metasurfaces, and FDTD Simulations of their Mueller Matrices

Abstract

Denne avhandlingen undersøker design, fabrikasjon og Finite-Difference Time-Domain (FDTD) simuleringer av optiske metasurfacer, med vekt p ̊a polarisasjon -splittende metasurfacer. Avhand- lingen fokuserer hovedsakelig p ̊a to typer metasurfaces: Gap Surface Plasmon (GSP) metasurfacer rettet mot ̊a oppn ̊a en større brytningsvinkel, og amorfe silisium (a-Si) søylebaserte metasurfaces med en integrert blender ̊apning. Fabrikasjonsprosessen for GSP metasurfaces ble gjennomført, til tross for noen manglende meta- atomer, sannsynligvis p ̊a grunn av et feil forhold mellom resist og metallisk lagtykkelse i lift- off prosessen. Design og innledende stadier av a-Si søyle metasurfaces ble fullført, selv om full fabrikasjon ikke ble oppn ̊add p ̊a grunn av tid og utstyrsbegrensninger. Integreringen av en aperture i metasurface-designet ble igangsatt og karakterisert, noe som indikerer nødvendigheten av videre undersøkelse. I tillegg til produksjon, ble en metode for ̊a trekke ut Mueller Matrices i FDTD-simuleringer utvikley, noe som gir et lovende grunnlag for videre bruk. Denne tilnærmingen er spesielt gunstig for store, ikke-periodiske metasurfaces, der FDTD tilbyr fordeler over Finite Element Method (FEM).

This thesis investigates the design, fabrication, and Finite-Difference Time-Domain (FDTD) simu- lations of optical metasurfaces, with an emphasis on polarization beam splitting metasurfaces. The study primarily focuses on two types of metasurfaces: Gap Surface Plasmon (GSP) metasurfaces aimed at achieving a greater angle of refraction than previous work, and amorphous silicon (a-Si) pillar-based metasurfaces with an integrated aperture for camera integration. The fabrication process of GSP metasurfaces was executed, despite some missing meta-atoms likely due to an incorrect ratio between resist and metallic layer thickness in the lift-off process. The design and preliminary stages of the a-Si pillar metasurfaces were completed, although full fabrication was not achieved due to time and equipment constraints. The integration of an aperture into the metasurface design was initiated and characterized with intensity measurements, indicating the necessity for further fine-tuning of process characteristics. In addition to manufacturing, a methodology for extracting Mueller Matrices in FDTD simulations was developed and successfully implemented, providing a promising basis for further refinement. This approach is particularly beneficial for large, non-periodic metasurfaces, where FDTD offers advantages over Finite Element Method (FEM).