Abstract-Conducting Helical Structures from Celery Decorated with a Metallic Conjugated Polymer Give Resonances in the Terahertz Range

Anders Elfwing, Carlito S. Ponseca Jr.,Liangqi Ouyang, Andrzej Urbanowicz, Aru–nas Krotkus, Deyu Tu, Robert Forchheimer,Olle Inganäs

http://onlinelibrary.wiley.com/doi/10.1002/adfm.201706595/full

A method to decorate cellulose-based helices retrieved from the plant celery with a conductive polymer is proposed. Using a layer-by-layer method, the decoration of the polyanionic conducting polymer poly(4-(2,3-dihydrothieno [3,4-b]-[1,4]dioxin-2-yl-methoxy)-1-butanesulfonic acid (PEDOT-S) is enhanced after coating the negatively charged cellulose helix with a polycationic polyethyleneimine. Microscopy techniques and two-point probe are used to image the structure and measure the conductivity of the helix. Analysis of the optical and electrical properties of the coated helix in the terahertz (THz) frequency range shows a resonance close to 1 THz and a broad shoulder that extends to 3.5 THz, consistent with electromagnetic models. Moreover, as helical antennas, it is shown that both axial and normal modes are present, which are correlated to the orientation and antenna electrical lengths of the coated helices. This work opens the possibility of designing tunable terahertz antennas through simple control of their dimensions and orientation.

Abstract-Tunable Antenna Coupled Intersubband Terahertz Detector

Nutan Gautam, Jonathan Kawamura, Nacer Chahat, Boris Karasik, Paolo Focardi, Samuel Gulkis, Loren Pfeiffer, Mark Sherwin

http://arxiv-web3.library.cornell.edu/abs/1410.5344

We report on the development of a tunable antenna coupled intersubband terahertz (TACIT) detector based on GaAs/AlGaAs two dimensional electron gas. A successful device design and micro-fabrication process have been developed which maintain the high mobility (1.1x106 cm2/V-s at 10K) of a 2DEG channel in the presence of a highly conducting backgate. Gate voltage-controlled device resistance and direct THz sensing has been observed. The goal is to operate as a nearly quantum noise limited heterodyne sensor suitable for passively-cooled space platforms.