Abstract-Wideband circular polarization converter based on graphene metasurface at terahertz frequencies

Chongyun Wang,  Ming Chen,  Houquan Liu,  Chuanxin Teng, Hongchang Deng,  Libo Yuan

https://www.spiedigitallibrary.org/journals/Optical-Engineering/volume-58/issue-4/043106/Wideband-circular-polarization-converter-based-on-graphene-metasurface-at-terahertz/10.1117/1.OE.58.4.043106.short?SSO=1

Linear-to-circular polarization converters are widely used in optical and microwave systems, but the polarization devices of traditional materials are untunable, and devices made of graphene materials can overcome this disadvantage. A circular polarization converter based on graphene metasurface is designed, whose properties are tunable over a broad range at terahertz frequencies. With appropriate structural parameters, simulations show that the axial ratio of reflected electromagnetic wave of the proposed device is lower than 3 dB in the frequency band of 2.25 to 2.475 THz, which means the linearly incident polarization can be converted to the circular polarization wave. The proposed design can also work when the electromagnetic wave is oblique incidence up to 40 deg with a high polarization conversion ratio. Moreover, the operating frequency band can be arbitrarily adjusted by applying a bias voltage.

© 2019 Society of Photo-Optical Instrumentation Engineers (SPIE) 0091-3286/2019/$25.00 © 2019 SPIE

Abstract-Dual-band superposition induced broadband terahertz linear-to-circular polarization converter

                                                                   

Xiao-Fei Zang, Su-Ji Liu, Han-Hong Gong, Yajun Wang, and Yi-Ming Zhu

https://www.osapublishing.org/josab/abstract.cfm?uri=josab-35-4-950

A reflective broadband terahertz (THz) linear-to-circular (LTC) polarization converter based on a single-layer ultrathin metasurface is designed and experimentally demonstrated. Two different-size rectangular ultrathin metasurface micro-structures are proposed to realize such a broadband THz LTC polarization converter with bandwidth ranging from 0.832 to 1.036 THz. The phase delay between two orthogonal resonance modes is −90°±5°$-90°\pm 5°$. These qualities are realized mainly by combining two separated LTC polarization conversion frequencies and the benefit of the coupling between two different-size rectangles. The calculated results indicate that the bandwidth of the LTC polarization converter is controlled via the dimensions and period of the structure. This kind of ultrathin broadband THz polarization converter can be widely applied into wireless communication, imaging, and detection, and can widen the path to designing novel functional THz devices.

© 2018 Optical Society of America

Abstract-Broadband tunable terahertz polarization converter based on graphene metamaterial

Shiwen Luo, Bin Li, Anlan Yu, Jun Gao, Xinbing Wang,  Duluo Zuo,

https://www.sciencedirect.com/science/article/pii/S0030401817311574

We design and numerically investigate a broadband tunable terahertz polarization converter based on graphene metamaterial. The converter presents a broad conversion band with high polarization conversion ratio (>0.95) in terahertz frequency over a bandwidth which is 25.8% of the central frequency. The converter can be dynamically tuned by varying the Fermi Energy of the graphene without changing the geometric structure. The converter shows high conversion ratio for a wide range of incident angles from 0 to 40°. By the scaling of the proposed structure, the broadband properties of the converter can be easily spread to other frequency. The proposed metamaterial offers an approach in the manipulation of the light polarization and has potential applications in imaging, sensing and communications.

Abstract-Ultrathin flexible terahertz polarization converter based on metasurfaces

Ultrathin flexible terahertz polarization converter based on metasurfaces

Weicheng Mo, Xuli Wei, Kejia Wang, Yao Li, and Jinsong Liu

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-24-12-13621

We present a method to design and fabricate a kind of converters based on flexible metasurfaces which can change the polarization state of an incident terahertz beam. The metasurface consists of a two-dimensional array of rectangular metallic antennas that can abruptly change the phase of the incoming terahertz beam. Experimentally demonstrated half-wave plates generate 0.1 THz beam with a π/2 polarization rotation. By slightly changing the structure of the converter, an elliptically or circularly polarized beam is expected to be obtained. These flexible terahertz converters may have many potential applications in terahertz technology.

© 2016 Optical Society of America

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