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Active control of chirality in the terahertz frequency range is of great importance in many scientific areas, which include research into fundamental optical phenomena, investigation of novel materials, spectroscopy, imaging, wireless communications and chemistry. The lack of efficient, integrated and fast-reconfigurable polarization modulators has hindered, so far, the full exploitation of applications in all the aforementioned fields. Metamaterials are artificial resonant elements possessing unique remarkable properties such as high efficiency and miniaturization capability. The interplay of metallic metamaterial arrays with electrostatically tunable monolayer graphene has been demonstrated to be a valid approach for the realization of a novel class of THz devices. In this work, the realization of active chiral graphene/metamaterial modulator is presented. The versatility of this experimental approach allowed the device integration with broadband sources such as terahertz time domain spectrometers as well as with quantum cascade lasers. A continuous rotation of the polarization plane > 30° has been reported with a reconfiguration speed > 5 MHz. These results pave the way to the integration of fast terahertz polarization modulators in all the applications where these devices are in great demand.

Metamaterials are engineered materials that gain their properties from the repeating patterns of their structures. Here we discuss paper-based metamaterials, with the honeycomb structure, and a possible auxetic design of them.Read Complete Article at ijSciences: V3201410597 AND DOI: http://dx.doi.org/10.18483/ijSci.597

There is increasing interest in the development of cost-effective, practical, portable, and disposable diagnostic devices suited to on-site detection and analysis applications, which hold great promise for global health care,[1,2] environmental monitoring,[3] water and food safety,[4] as well as medical and threat reductions.[5] Lab-on-a-chip (LOC) devices, which scale single or multiple lab processes down to chip format (millimeters to a few square centimeters in size), facilitated by micro- and nanoscale technologies have attracted significant attention because of their small sample volume requirements and excellent portability.[6] Various LOC devices have been designed and fabricated in the past two decades, most of which involve a lithography-based patterning process on a solid or elastomeric substrate, such as glass or plastic, for a variety of functionalities that include sample preparation,[7] microfluidic mixing,[8] biochemical reactions,[9] and analysis.[10]