Abstract-Refractive indices and birefringence of hybrid liquid crystal - nanoparticles composite materials in the terahertz region

E. Mavrona^1,2,a), U. Chodorow³, M. E. Barnes¹, J. Parka^3,4, N. Palka⁵, S. Saitzek², J.-F. Blach², V. Apostolopoulos¹ and M. Kaczmarek¹
 HIDE AFFILIATIONS
1 School of Physics and Astronomy, University of Southampton, Southampton, SO17 1BJ, United Kingdom
2 CNRS UMR 8181, Unité de Catalyse et de Chimie du Solide - UCCS, UArtois, Faculté des Sciences Jean Perrin, SP18, F-62307 Lens Cedex, France
3 Institute of Applied Physics, Military University of Technology, Warsaw, Poland
4 Institute of Microelectronics and Optoelectronics, Warsaw University of Technology, Warsaw, Poland
5 Institute of Optoelectronics, Military University of Technology, Warsaw, Poland
a) Electronic mail: em3e12@soton.ac.uk
AIP Advances 5, 077143 (2015); http://dx.doi.org/10.1063/1.4927392

http://scitation.aip.org/content/aip/journal/adva/5/7/10.1063/1.4927392

We show that a hybrid LC-ferroelectric nanoparticle suspension of liquid crystal E7 doped with BaTiO3 nanoparticles leads to 10% increase in birefringence in the THz region of spectrum as compared to pure E7. Doped liquid crystals can be used to increase performance of THz modulators and waveplates. BaTiO3 nanoparticles used in the mixture were synthesised with the sol gel technique, and their refractive index has been measured in THz in powder form and in solution.

Abstract-Fluence and polarisation dependence of GaAs based Lateral Photo-Dember terahertz emitters

D. McBryde, M. E. Barnes, S. A. Berry, P. Gow, H. E. Beere, D. A. Ritchie, and V. Apostolopoulos  »View Author Affiliations

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-22-3-3234

Optics Express, Vol. 22, Issue 3, pp. 3234-3243 (2014)
http://dx.doi.org/10.1364/OE.22.003234

We characterise THz output of lateral photo-Dember (LPD) emitters based on semi-insulating (SI), unannealed and annealed low temperature grown (LTG) GaAs. Saturation of THz pulse power with optical fluence is observed, with unannealed LTG GaAs showing highest saturation fluence at 1.1 ± 0.1 mJ cm⁻². SI-GaAs LPD emitters show a flip in signal polarity with optical fluence that is attributed to THz emission from the metal-semiconductor contact. Variation in optical polarisation affects THz pulse power that is attributed to a local optical excitation near the metal contact.

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