Anomalous Resonance Frequency Shift in Liquid Crystal-Loaded THz Metamaterials

TL;DR

This study reveals that in terahertz liquid crystal-metamaterials, the resonance frequency shifts differ between complementary patterns due to alignment mismatch, with potential for shifts beyond expected limits caused by liquid crystal nonlinearity.

Contribution

It demonstrates the anomalous resonance frequency shift in liquid crystal-loaded metamaterials, highlighting the impact of liquid crystal alignment and nonlinear effects on resonance tuning.

Findings

Resonance sensitivity varies between complementary patterns due to alignment mismatch.

Resonance can be shifted beyond traditional limits by exploiting liquid crystal nonlinearity.

Experimental evidence of anomalous frequency shifts in hybrid metamaterials.

Abstract

Babinet complementary patterns of a spectrally tunable metamaterial incorporating a nematic liquid crystal are normally assumed to exhibit the same tuning range. Here we show that for a hybrid, terahertz liquid crystal-metamaterial, the sensitivity of its resonances to the variations of the refractive index differs substantially for the two complementary patterns. This is due to a mismatch between the alignment of the liquid crystal and the direction of the local electric field induced in the patterns. Furthermore, and more intriguingly, our experimental data indicate that it is possible to shift the resonance of the positive metamaterial pattern beyond the limit imposed by the alignment mismatch. Our analysis suggests that the observed anomalous frequency shift result from the orientational optical nonlinearity of a nematic liquid crystal.