Abstract-Design and fabrication of 3-D printed conductive polymer structures for THz polarization control

A. I. Hernandez-Serrano, Qiushuo Sun, Elizabeth G. Bishop, Elliott R. Griffiths, Christopher P. Purssell, Simon J. Leigh, J. Lloyd-Hughes, and Emma Pickwell-MacPherson

Fig. 1 (a) Diagram of the proposed polarizer; (b) Photograph of the printed devices; (c) and (d) show the refractive index and absorption coefficient of CPLA, respectively.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-27-8-11635

In this paper, we numerically and experimentally demonstrate the inverse polarization effect in three-dimensional (3-D) printed polarizers for the frequency range of 0.5 - 2.7 THz. The polarizers simply consist of 3-D printed strip lines of conductive polylactic acid (CPLA, Proto-Pasta) and do not require a substrate or any further metallic deposition. The experimental and numerical results show that the proposed structure acts as a broadband polarizer between the range of 0.3 THz to 2.7 THz, in which the inverse polarization effect is clearly seen for frequencies above 0.5 THz. In the inverse polarization effect, the transmission of the transverse electric (TE) component exceeds that of the TM component, in contrast to the behavior of a typical wire-grid polarizer. We show how the performance of the polarizers depends on the spacing and thickness of the CPLA structure; extinction ratios higher than 20 dB are achieved. This is the first report using CPLA to fabricate THz polarizers, demonstrating the potential of using conductive polymers to design THz components efficiently and robustly.

© 2019 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Polarization control of terahertz radiation from two-color femtosecond gas breakdown plasma

O. Kosareva, M. Esaulkov, N. Panov, V. Andreeva, D. Shipilo, P. Solyankin, A. Demircan, I. Babushkin, V. Makarov, U. Morgner, A. Shkurinov, and A. Savel’ev

http://www.etoponline.org/ol/abstract.cfm?uri=ol-43-1-90

We individually control polarizations of 800 and 400 nm beams, which form a two-color femtosecond plasma filament in air irradiating a linear-to-elliptical THz signal. We detected a threshold-like appearance of THz ellipticity at the angle of ∼85°$\sim 85°$ between the fundamental and second-harmonic field polarization directions. The simulations confirm the abrupt change of THz polarization and reveal that the weak ellipticity of the second harmonic is sufficient to generate essentially elliptical THz radiation.

© 2017 Optical Society of America

Abstract-Terahertz Focusing and Polarization Control in Large-Area Bias-Free Semiconductor Emitters

Joanna L. Carthy, 

Paul C. Gow, 

Sam A. Berry, 

Ben Mills, 

Vasilis Apostolopoulos

https://link.springer.com/article/10.1007%2Fs10762-017-0452-4

We show that, when large-area multiplex terahertz semiconductor emitters, that work on diffusion currents and Schottky potentials, are illuminated by ultrashort optical pulses they can radiate a directional electromagnetic terahertz pulse which is controlled by the angular spectrum of the incident optical beam. Using the lens that focuses the incident near-infrared pulse, we have demonstrated THz emission focusing in free space, at the same point where the optical radiation would focus. We investigated the beam waist and Gouy phase shift of the THz emission as a function of frequency. We also show that the polarization profile of the emitted THz can be tailored by the metallic patterning on the semiconductor, demonstrating radial polarization when a circular emitter design is used. Our techniques can be used for fast THz beam steering and mode control for efficiently coupling to waveguides without the need for THz lenses or parabolic mirrors.

Abstract-Ultrafast polarization control of zero-bias photocurrent and terahertz emission in hybrid organic perovskites

Petr A. Obraztsov, Dmitry Lyashenko, Pavel A. Chizhov, Kuniaki Konishi, Natsuki Nemoto, Makoto Kuwata-Gonokami, Eric Welch, Alexander N. Obraztsov, Alex Zakhidov

(Submitted on 26 Oct 2017)

https://arxiv.org/abs/1710.09728

Methylammonium lead iodide (MAPI) is a benchmark hybrid organic perovskite material, which is used for the low-cost, printed solar cells with over 20 percent power conversion efficiency. Yet, the nature of light-matter interaction in MAPI as well as the exact physical mechanism behind device operation is currently debated. Here we report room temperature, ultrafast photocurrent and freespace terahertz (THz) emission generation from unbiased MAPI induced by 150 fs light pulses. Polarization dependence of the observed photoresponse is consistent with the Bulk Photovoltaic Effect (BPVE) caused by a combination of injection and shift currents. We believe that this observation of can shed light on low recombination, and long carrier diffusion lengths due to indirect bandgap. Moreover, ballistic by nature shift and injection BPVE photocurrents may enable third generation perovskite solar cells with efficiency that exceed the Shockley_Queisser limit. Our observations also open new venues for perovskite spintronics and tunable THz sources.

Abstract-Polarization dependent terahertz generation efficiency by optical rectification in LiNbO3

Kun Meng, Sen-Cheng Zhong, Li-Guo Zhu, Qiao Liu, Ze-Ren Li

China Academy of Engineering Physics (China)

http://proceedings.spiedigitallibrary.org/proceeding.aspx?articleid=2089967

Proc. SPIE 9444, International Seminar on Photonics, Optics, and Its Applications (ISPhOA 2014), 94440J (January 9, 2015); doi:10.1117/12.2075161

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Optical rectification of laser pulses in LiNbO3 by tilted-pulse-front pumping (TPFP) is a powerful way to generate terahertz(THz) pulses. However, comprehensive theoretical analysis is still lack. In this work, we first established and presented a detailed theoretical model for TPFP scheme, which then was used to analyze the pump beam polarization dependent terahertz pulses generated by this scheme. The results indicate that one can change the polarization state of the terahertz pulse by changing the pump beam polarization. A scheme using tilted-pulse-front pumping was also set up, and the generated terahertz pulses have maximal conversion efficiency when the pump beam electric field vector is parallel to the crystal axis, which is consistent with theoretical model. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

Abstract-Subcycle control of terahertz waveform polarization using all-optically induced transient metamaterials

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N Kamaraju^1,2, Andrea Rubano^1,3, Linke Jian⁴, Surajit Saha⁴, T Venkatesan⁴, Jan Nötzold¹, R Kramer Campen¹, Martin Wolf¹ and Tobias Kampfrath¹

1. ¹Fritz Haber Institute of the Max Planck Society, 14195 Berlin, Germany
2. ²Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
3. ³CNR-SPIN, Dipartimento di Fisica, Università di Napoli Federico II, Napoli, Italy
4. ⁴NUSNNI-Nanocore, National University of Singapore, Singapore

Correspondence: Dr N Kamaraju, Department of Electrical, Computer, and Systems Engineering, Rensselaer Polytechnic Institute, Troy, NY 12180, USA. E-mail: nkamaraju@gmail.com; Dr T Kampfrath, Fritz Haber Institute of the Max Planck Society, Faradayweg 4–6, 14195 Berlin, Germany. E-mail: kampfrath@fhi-berlin.mpg.de

Received 26 July 2013; Revised 18 October 2013; Accepted 13 November 2013, Published online February 28 2014

http://www.nature.com/lsa/journal/v3/n2/full/lsa201436a.html

Coherent radiation with frequencies ranging from 0.3 to 30 THz has recently become accessible using femtosecond laser technology. These terahertz (THz) waves have already been applied in spectroscopy and imaging and can be manipulated using static optical elements such as lenses, polarizers and filters. However, ultrafast modulation of THz radiation is required as well, for instance, in short-range wireless communication or for preparing shaped THz transients for the coherent control of numerous material excitations. Here, we demonstrate an all-optically created transient metamaterial that allows us to manipulate the polarization of THz waveforms with subcycle switch-on times. The polarization-modulated pulses are potentially interesting for controlling elementary motions such as the vibration of crystal lattices, the rotation of molecules and the precession of spins.