Low-Bias THz Amplitude Modulator Based on Split-Ring Resonators and Graphene

Riccardo Degl'Innocenti , Davide Stephan Jessop , Yash Diptesh Shah , Juraj Sibik , J Axel Zeitler , Piran Ravichandran Kidambi , Stephan Hofmann , Harvey E Beere , and David Ritchie


Abstract

Split-ring resonators represent the ideal route to achieve optical control of the incident light at THz frequencies. These sub-wavelength metamaterial elements exhibit broad resonances that can be easily tuned lithographically. We realized a design based on the interplay between the resonances of metallic split-rings and the electronic properties of a monolayer graphene integrated in a single device. By varying the major carrier concentration of graphene, an active modulation of the optical intensity was achieved in the frequency range between 2.2 THz and 3.1 THz, achieving a maximum modulation depth of 18\%, with a bias as low as 0.5 V.

This study was performed using TeraView's TPI Imaga 2000 system. (TeraView, Cambridge, UK)

Full Article: http://pubs.acs.org/doi/abs/10.1021/nn406136c

Towards optoelectronic detection of explosives

Opto-Electronics Review, June 2013, Volume 21, Issue 2, pp 210-219

doi 10.2478/s11772-013-0082-x

Authors: J. Wojtas, T. Stacewicz, Z. Bielecki, B. Rutecka, R. Medrzycki, J. Mikolajczyk
More details at: http://link.springer.com/article/10.2478/s11772-013-0082-x

Abstract

Detection of explosives is an important challenge for contemporary science and technology of security systems. We present an application of NOx sensors equipped with concentrator in searching of explosives. The sensors using CRDS with blue — violet diode lasers (410 nm) as well as with QCL lasers (5.26 μm and 4.53 μm) are described. The detection method is based either on reaction of the sensors to the nitrogen oxides emitted by explosives or to NOx produced during thermal decomposition of explosive vapours. For TNT, PETN, RDX, and HMX the detection limit better than 1 ng has been achieved.

... Time domain spectroscopy (TDS) is especially useful in the THz range [12,13]. Observation of explosives' transmission and reflection are conducted by using TeraView TPS Spectra 3000 instrument at the Institute of Optoelectronics, MUT ...

Author Affiliations: Institute of Optoelectronics, Military University of Technology, 2 Kaliskiego Str., 00-908, Warsaw, Poland

In 2011 TeraView supplied two TPS Spectra 3000 systems with a stand-off explosives detection module and a fibre-fed scanning system with multiple gantry options for research into terahertz imaging and non-destructive testing. Military University of Technology (MUT) in Poland is one of the country’s most prestigious research institutes for terahertz research and materials characterisation. Read more...