Terahertz Polarizers Based on 2D Ti 3 C 2 T z MXene: Spin Cast from Aqueous Suspensions

Abstract

Herein, the fabrication of terahertz (THz) polarizers is reported on by simply spin casting two-dimensional (2D) MXene Ti3C2Tz nanosheets on a photolithographically patterned THz-transparent substrate and subsequent immersion in acetone. Lines 30?nm-thick and 10?20??m wide result in electric field (E) extinction ratios (ER) of up to 3?dB, or power ER of up to 6?dB. Simulations show the possibility of achieving ER beyond 16?dB, or power ER higher than 32?dB by increasing the thickness of the MXene lines to 1.5?2??m and optimizing the metasurface patterns. The Ti3C2Tz nanosheets are solution-processed and can be deposited on a variety of substrates, including flexible ones. Once encapsulated, chemically stable THz polarizers, that combine high performance and low production costs, can be readily manufactured, with characteristics that compare favorably with the much more involved metallic wire grid polarizers, including gold and tungsten. Moreover, recent demonstration of dynamic tunability of Ti3C2Tz THz conductivity by ultrafast optical pulses opens the possibility of using MXene wire-grids in high-speed THz modulators.