Computational Electromagnetic Modeling of Metasurface Optical Devices with Defect Study
Abstract
One of the first fabricated met surface optical devices, the in-plane V-antenna lenses, were plagued by a fundamental transmission limit (<25%). Two distinct sets of Out-of-Plane phase elements were designed with improved transmission (approx. 60%). These were fabricated as beamsteerers and characterized in terms of their Bidirectional Transmittance Distribution Function measured as a function of scatter angle. Experimental data from the beamsteerers was analyzed via simulations using a finite element method (FEM). The measurements showed the designed beamsteering, but also a strong zero-order diffraction not present in the simulations, which motivated this study to understand what was causing these differences. To that end, FEM models which addressed specific defects and models that adjusted the coupling of the device were developed and these well-predicted the measured data. These models provided an understanding of the near-field effects that caused this behavior, and provided strong evidence that the amplitude and phase imparted by the fabricated phase elements must be different than what was designed, either because their placement is different than what was designed or their design was slightly changed during fabrication. Future work will focus on studying the impact of coupling and leveraging the lessons learned into future OOP design-fabrication-test iterations.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 2020
- Accession Number
- AD1145414
Entities
People
- Carlos D. Diaz
Organizations
- Air Force Institute of Technology