Liquid Crystal Based Terahertz Phase Shifter with Bi-Layer Structure

We propose and demonstrate a liquid crystal (LC) based terahertz phase shifter with a thick ( $550 \ \mu \mathrm{m}$ in total) bi-Iayer LC cell structure incorporating a thin transparent polymeric intermediate layer. The present phase shifter exhibited remarkable performance improvement. The phase shift increased from 94° to 111° threshold and drive voltages decreased from 2.2 $\mathbf{V_{RMS}}$ to $\mathbf{1 V_{RMS}}$ and from $\mathbf{10 V_{RMS}}$ to $\mathbf{8.4 V_{RMM}}$ , respectively, in comparison with those for single-layer cell structure.