Enhanced Performance of Fe/WO3 Terahertz Dielectric Lenses

Abstract

Herein transparent iron nanosheets deposited by the ionic coating technique onto glass and WO₃ dielectric lenses are studied and characterized. The thickness of Fe nanosheets is varied in the range of 70–350 nm. It is observed that the transmittance and reflectance of the Fe nanosheets are highly affected by the layer roughness. Coating of iron nanosheets onto WO₃ dielectric lenses increases the light absorption of WO₃ by more than 240 times and red-shifts the energy bandgap. Remarkable enhancements in the dielectric constant and in the optical conductivity are achieved via Fe coatings. In addition, iron coated dielectric lenses show higher terahertz cutoff limits varying in the range of 1.0–30 THz. Iron nanosheets remarkably increase the free charge carrier density and plasmon frequency in the infrared range of light. Moreover, the temperature dependent electrical conductivity shows high temperature stability and an increased electrical conductivity by more than 7 orders of magnitude by coating WO₃ with 70 nm thick Fe nanosheets. The stability of the electrical conductivity at low temperatures and the wide range of terahertz cutoff limits in addition to the well-enhanced light absorbability makes the iron coated tungsten oxide dielectric lenses promising for multifunction optoelectronic applications.