Abstract-Review on polarimetric terahertz spectroscopy

 

Yandong Gong,   Zhuo Zhang,   Ke Li,   Wenxu Ren, 

https://onlinelibrary.wiley.com/doi/abs/10.1002/mop.32809

Unique features of terahertz (THz) wave have made THz spectroscopy a potential and ideal tool for spectroscopy analysis. When a conventional THz spectroscopy system is used to measure a sample with birefringence, sometimes it is highly possible to misinterpret a polarization filter effect as normal spectral absorption, thus leads to a wrong identification and conclusion. Polarimetric terahertz spectroscopy (PTS) is one kind of newly emerged technology upgraded from conventional terahertz spectroscopy, in addition to all the traditional functions, it is able to automatically measure additional state of polarization of THz wave, as well as additional polarization information of samples. Here in this article we will comprehensively review the principle and progress of such PTS technology.

Abstract-Terahertz All-Dielectric Magnetic Mirror Metasurfaces

Zhijie Ma, Stephen M. Hanham, Pablo Albella, Binghao Ng, Hsiao Tzu Lu, Yandong Gong, Stefan A. Maier and Minghui Hong

http://pubs.acs.org/doi/abs/10.1021/acsphotonics.6b00096?journalCode=apchd5

We demonstrate an all-dielectric metasurface operating in the terahertz band that is capable of engineering a reflected beam's spatial properties with high efficiency. The metasurface is formed from an array of silicon cube resonators which simultaneously support electric and magnetic dipolar Mie resonances. By controlling the interference between these modes, the amplitude and phase of a reflected wave can be arbitrarily controlled over a sub-wavelength area. We demonstrate the flexibility and utility of this metasurface by optimizing the surface to produce several reflected beam types including vortex and Bessel beams; the latter being useful for diffraction-free point-to-point terahertz communications. Additionally, we show theoretically and experimentally how the metasurface can produce an all-dielectric magnetic mirror in the terahertz band.

Abstract- An ultrathin terahertz quarter-wave plate using planar babinet-inverted metasurface

An ultrathin terahertz quarter-wave plate using planar babinet-inverted metasurface Dacheng Wang, Yinghong Gu, Yandong Gong, Cheng-Wei Qiu, and Minghui Hong  »View Author Affiliations Optics Express, Vol. 23, Issue 9, pp. 11114-11122 (2015) http://dx.doi.org/10.1364/OE.23.011114

http://www.opticsinfobase.org/oe/abstract.cfm?uri=oe-23-9-11114

Optics Express, Vol. 23, Issue 9, pp. 11114-11122 (2015)

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Metamaterials promise an exotic approach to artificially manipulate the polarization state of electromagnetic waves and boost the design of polarimetric devices for sensitive detection, imaging and wireless communication. Here, we present the design and experimental demonstration of an ultrathin (0.29λ) terahertz quarter-wave plate based on planar babinet-inverted metasurface. The quarter-wave plate consisting of arrays of asymmetric cross apertures reveals a high transmission of 0.545 with 90 degrees phase delay at 0.870 THz. The calculated ellipticity indicates a high degree of polarization conversion from linear to circular polarization. With respect to different incident polarization angles, left-handed circular polarized light, right-handed circular polarized light and elliptically polarized light can be created by this novel design. An analytical model is applied to describe transmitted amplitude, phase delay and ellipticitiy, which are in good agreement with the measured and simulated results. The planar babinet-inverted metasurface with the analytical model opens up avenues for new functional terahertz devices design.

© 2015 Optical Society of America

Abstract-Development of a Stokes polarimeter system for high terahertz frequency region

Takashi Notake1, Banghong Zhang2, Yandong Gong2 and Hiroaki Minamide1

notake@riken.jp

http://iopscience.iop.org/1347-4065/53/9/092601/pdf/1347-4065_53_9_092601.pdf

1 Tera-Photonics Laboratory, RIKEN RAP, Sendai 980-0845, Japan
2 Institute for Infocomm Research, 138632 Singapore
 

Takashi Notake et al 2014 Jpn. J. Appl. Phys. 53 092601. doi:10.7567/JJAP.53.092601
Received 19 March 2014, accepted for publication 17 July 2014. Published 1 September 2014.
© 2014 The Japan Society of Applied Physics

We have developed a Stokes polarimeter system which can be used at an arbitrary, wide terahertz frequency region by using a wave plate and difference frequency generation system with DAST crystal (DAST-DFG). Conventional wave plates made of dielectric materials with intrinsic birefringence at optical wavelengths cannot be applied directly to terahertz frequencies because of the large absorption loss. High resistivity silicon, which remains transparent even at the higher terahertz frequency region, was selected as the wave plate material. Although the silicon has intrinsic birefringence hardly, large form birefringence can be successfully induced by fabricating a one-dimensional grating structure of sub-wavelength scale on its surface and proper operation as wave plate can be confirmed. By using the wave plate with a polarizer on DAST-DFG system, Stokes polarimeter system can be also successfully developed. Our approach can be extended to an arbitrary, wide terahertz frequency region and open many terahertz-wave applications associated with polarization physics at there.