High Fill-Factor Substrate-Based Wire-Grid Polarizers With High Extinction Ratios

Low-cost, substrate-based, millimeter-wave-to-THz wire-grid polarizers have been fabricated on crystalline-quartz substrates using planar processing techniques. The polarizers achieve high extinction ratios (at least 60 dB) with a single layer, while maintaining low insertion loss (a few decibels) by taking advantage of previously under-utilized “spoof” surface-plasmon effects. Full-wave finite-element simulations done with High Frequency Structure Simulator and experiments both show that metal fill-factors upwards of 90% greatly improve polarizer extinction ratio. The extinction ratio of high fill-factor polarizers exceeds that of a commercial free-standing wire grid by up to 20 dB at normal incidence.