High transmittance and broaden bandwidth through the morphology of anti-relfective layers on THz polarizer with Si substrate

To improve the transmittance of THz component and overcome the difficulties of fragile structure as well as ensuring precise alignment of existing methods, a new method involving the mature 3DIC through-silicon via (TSV) technology has been proposed to make anti-reflection layer with suitable effective refractive index based on the robustness of Si wafer. Cu wire-grid polarizers were also fabricated on wafer. The THz polarizers were completed after wafer bonding with Cu sealing ring and In/Sn guard ring. Not only the new method is easier for production with better performance, but also the silicon substrate has several advantages. The novel method has proven that THz optical component could be constructed with a nearly 100% transmittance, or widened the transmittance spectrum range from 0.5 to 2 THz when transmittances is sacrificed to 70% instead of a near 100%. Furthermore, a robust structure could also be expected with broadband transmission and excellent extinction ratio. It is properly optimized for mass production because the fabrication method could be easily done and does not required high cost.