Friday, 27 May 2016

TeraView present poster at this years ETCC conference

TeraView's Dr Robert May gave a successful presentation at this years ETCC congress on our new Non-Contact, Multi-Layer Coating Thickness Sensor.

The sensor can determine the individual thickness of multiple paint layers on both metallic and non-metallic substrates and offers significant benefits over existing techniques, representing a significant leap beyond the current method of measurement for quality and process control in automotive paint application. See our product page for more information.

Thanks to all involved for putting on a great event!

Tuesday, 10 May 2016

Electric Properties of Graphene-Based Conductive Layers from DC Up To Terahertz Range

Pawel Kopyt ; Bartlomiej Salski ; Przemyslaw Zagrajek ; Daniel Janczak 


This paper describes results obtained using a hybrid measurement methodology employed to investigate electric properties of thin conductive layers based on graphene nanoplatelets in the frequency band spanning from dc up to terahertz range. As many as four different measurement methods were employed to cover the band of interest, including the terahertz time-domain spectroscopy and the Fourier-transform infrared spectroscopy besides resonator techniques applicable in the microwave band and the four-point dc technique. Raw measurement data obtained using these approaches were processed and based on the results a relationship between frequency and sheet resistance for various types of new graphene-based conductive layers was extracted. Eventually, several models that help to explain the observed behavior of each of the analyzed conductive inks were proposed.

Full article here

Thursday, 5 May 2016

Electron beam irradiation of materials and components to be used in mid-IR spectroscopy

Dan Sporea ; Laura Mihai ; Adelina Sporea ; Gabriela Crăciun ; Elena Mănăilă


In this paper, we report the results concerning electron beam irradiation of mid-IR windows and mid-IR detectors for possible use in trace gas detection systems, in the 1 μm to 5 μm spectral range under ionizing radiation conditions. Four windows materials (CaF2, BaF2, ZnSe, and sapphire) for the mid-IR were tested as they were exposed to electron beam irradiation at a dose rate of 4 kGy/min, for doses from 0.5 kGy to 2.2 kGy.

Two IR detectors (photoconductive – PbSe, photovoltaic – InAs) were subjected to the same type of irradiation at dose rate of 4 kGy/min, in three subsequent exposures, for a total dose up to 6.8 kGy. Before the irradiation and after each irradiation step the windows were measured as it concerns the spectral optical transmittance, spectral optical diffuse reflectance, and, in the THz range (0.06 THz – 3 THz), the dielectric constant and the refractive index were evaluated. THz imaging analysis of the irradiated samples was done. For the IR detectors we measured at different irradiation stages the spectral responsivity and the dark current. The most affected by electron beam irradiation was the CaF2 window, in the spectral interval 250 nm – 800 nm.

The spectral transmittance of the four windows remained unchanged after their exposure to ionizing radiation in the near-IR and mid-IR. Noticeable variations of the spectral responsivity appeared upon electron beam irradiation in the case of the InAs detector. © (2016) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.


Tuesday, 3 May 2016

Graphene based plasmonic terahertz amplitude modulator operating above 100 MHz

D. S. Jessop, S. J. Kindness, L. Xiao, P. Braeuninger-Weimer, H. Lin, Y. Ren, C. X. Ren, S. Hofmann, J. A. Zeitler, H. E. Beere, D. A. Ritchie and R. Degl'Innocenti


The terahertz (THz) region of the electromagnetic spectrum holds great potential in many fields of study, from spectroscopy to biomedical imaging, remote gas sensing, and high speed communication. To fully exploit this potential, fast optoelectronic devices such as amplitude and phase modulators must be developed. In this work, we present a room temperature external THz amplitude modulator based on plasmonic bow-tie antenna arrays with graphene. By applying a modulating bias to a back gate electrode, the conductivity of graphene is changed, which modifies the reflection characteristics of the incoming THz radiation. The broadband response of the device was characterized by using THz time-domain spectroscopy, and the modulation characteristics such as the modulation depth and cut-off frequency were investigated with a 2.0 THz single frequency emission quantum cascade laser. An optical modulation cut-off frequency of 105 ± 15 MHz is reported. The results agree well with a lumped element circuit model developed to describe the device.

False detection of dangerous and neutral substances in commonly used materials by means of the standard THz time domain spectroscopy

V. A. Trofimov, S. A. Varentsova


Essential limitations of the standard THz Time Domain Spectroscopy (TDS), which lead to false detection of dangerous and neutral substances in commonly used materials, are demonstrated using the physical experiment with chocolate under real conditions as well as with semiconductors under laboratory conditions. To overcome this disadvantage, we propose using the time-dependent spectrum of the THz pulse, transmitted through or reflected from a substance. For quality assessment of the standard substance absorption frequency presence in the signal under analysis, we use time-dependent integral correlation criteria. The influence of aperture placed in front of the sample on spectral properties of silicon wafers with different resistivity is demonstrated as well.