TUNABLE TERAHERTZ FISHNET METAMATERIAL

Abstract

A tunable fishnet metamaterial (TFMM) was designed and fabricated to prove its potential in controlling terahertz radiation (0.1 THz~10THz). A model to retrieve refractive index of single layer fishnet metamaterial (SLFM) was developed and applied to study the tunable frequency range of TFMM. Reference planes that define the material boundaries of SLFM and multilayer fishnet metamaterial (MLFM) were investigated to show that the material property of fishnet metamaterial is a function of layers. The issue of applying current model to MLFM was discussed. The TFMM infiltrated with a voltage-controllable polymer dispersed liquid crystal (PDLC) was fabricated and tested by terahertz time domain spectroscopy (THz-TDS). An encapsulating technique that covers PDLC with a polyimide layer (skin layer) was applied to prevent volatile liquid crystal from escaping the PDLC and enable the deposition of metal layer. Concept of tuning TFMM infiltrated with PDLC (PDLC-TFMM) was proven by measuring the frequency shift in the reflection coefficient. The negative refractive index of PDLC-TFMM was achieved. The reliability issue of current PDLC-TFMM was discussed.