Abstract-Plasmonic absorption characteristics based on dumbbell-shaped graphene metamaterial arrays

Chunlian Cen, Jiajia Chen, Hang Lin, Cuiping Liang, Jing Huang, Xifang Chen, Yongjian Tang, Zao Yi, Xibin Xu, Shuyuan Xiao

https://arxiv.org/abs/1802.10285

In this paper, we proposed a theoretical model in the far-infrared and terahertz (THz) bands, which is a dumbbell-shaped graphene metamaterial arrays with a combination of graphene nanorod and two semisphere-suspended heads. We report a detailed theoretical investigation on how to enhance localized electric field and the absorption in the dumbbell-shaped graphene metamaterial arrays. The simulation results show that by changing the geometrical parameters of the structure and the Fermi level of graphene, we can change the absorption characteristics. Furthermore, we have discovered that the resonant wavelength is insensitive to TM polarization. In addition, we also find that the double-layer graphene arrays have better absorption characteristics than single-layer graphene arrays. This work allows us to achieve tunable terahertz absorber, and may also provide potential applications in optical filter and biochemical sensing.

Abstract-Plasmon-induced transparency in graphene-based terahertz metamaterials

Koijam Monika Devi, Maidul Islam, Dibakar Roy Chowdhury, Amarendra K. Sarma,  Gagan Kumar,


http://iopscience.iop.org/article/10.1209/0295-5075/120/27005/meta


Plasmon-induced transparency (PIT) effect in a terahertz graphene metamaterial is numerically and theoretically analyzed. The proposed metamaterial comprises of a pair of graphene split ring resonators placed alternately on both sides of a graphene strip of nanometer scale. The PIT effect in the graphene metamaterial is studied for different vertical and horizontal configurations. We have shown that the PIT effect can be tuned by varying the Fermi energy of the graphene layer. A theoretical model using the three-level plasmonic system is established in order to validate the numerical results. Our studies could be significant in designing graphene-based frequency agile ultra-thin devices for terahertz applications.

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-Plasmon induced transparency in graphene based terahertz metamaterials

Koijam Monika Devi, M. Islam, Dibakar R. Chowdhury, Amarendra K. Sarma, Gagan Kumar

https://arxiv.org/abs/1711.03775

Plasmon induced transparency (PIT) effect in a terahertz graphene metamaterial is numerically and theoretically analyzed. The proposed metamaterial comprises of a pair of graphene split ring resonators placed alternately on both sides of a graphene strip of nanometer scale. The PIT effect in the graphene metamaterial is studied for different vertical and horizontal configurations. Our results reveal that there is no PIT effect in the graphene metamaterial when the centers of both the split ring resonators and the graphene strip are collinear to each other. This is a noteworthy feature, as the PIT effect does not vanish for similar configuration in a metal-based metamaterial structure. We have further shown that the PIT effect can be tuned by varying the Fermi energy of graphene layer. A theoretical model using the three level plasmonic system is established in order to validate the numerical results. Our studies could be significant in designing graphene based frequency agile ultra-thin devices for terahertz applications.

Abstract-Dynamically controlled electromagnetically induced transparency in terahertz graphene metamaterial for modulation and slow light applications

Xunjun He, Yuan Yao, Xingyu Yang, Guangjun Lu, Wenlong Yang, Yuqiang Yang, Fengmin Wu, Zhigang Yu, Jiuxing Jiang,

http://www.sciencedirect.com/science/article/pii/S0030401817307745

By patterning two graphene resonators on a SiO₂/Si substrate, a dynamically controlled electromagnetically induced transparency (EIT) in the terahertz graphene metamaterial was numerically studied through tuning the structural parameter and Fermi energy of graphene. The calculated surface current distributions demonstrate that the distinct EIT window in the graphene metamaterial results from the near-field coupling of two graphene resonators. Moreover, the EIT window can be actively controlled by tuning Fermi energy combined states of two resonators. When the Fermi energy combined state of two resonators changes from (0.21 and 0.16 eV) to (0.4 and 0.11 eV), the amplitude modulation depth of the EIT peak is 97.8% at 0.45 THz, and the corresponding enhanced factor of group delay with 6 times is obtained. This study offers an alternative tuning method to existing optical, thermal, and relative distance tuning, delivering a promising potential for designing active and miniaturized THz devices.

Abstract-Tunable ultrasensitive terahertz sensor based on complementary graphene metamaterials

Xunjun He,   Qingfei Zhang,   Guangjun Lu,   Guobing Ying,  Fengmin Wu and   Jiuxing Jiang  

RSC Adv., 2016, Accepted Manuscript

DOI: 10.1039/C5RA21974D
Received 11 Mar 2016, Accepted 12 May 2016
First published online 23 May 2016
http://pubs.rsc.org/en/Content/ArticleLanding/2016/RA/C5RA21974D?utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+rss%2Fra+%28RSC+-+RSC+Adv.+latest+articles%29#!divAbstract

In this paper, we propose an ultrasensitive terahertz sensor based on the complementary graphene metamaterial composed of wire-slot and split-ring resonator slot array structure. The destructive interference between two resonators gives rise to a reflection peak enabling ultrasensitive sensing, and sensitivity of 177.7GHz/RIU and FOM of 59.3 can be obtained for the proposed sensor. More importantly, this sensor can not only enhance the absorption of biomelecules and sensing performance, but also dynamically tune the sensing range by shifting the Fermi energy. In addition, the influences of the lateral displacement on the sensing performance are also investigated to improve the sensitivity of sensor. Therefore, this method opens up opportunities for efficiently sensing several organic, explosive, and biomolecules.

Abstract-Tunable beam steering enabled by graphene metamaterials

B. Orazbayev, M. Beruete, and I. Khromova
https://www.osapublishing.org/oe/abstract.cfm?uri=oe-24-8-8848

We demonstrate tunable mid-infrared (MIR) beam steering devices based on multilayer graphene-dielectric metamaterials. The effective refractive index of such metamaterials can be manipulated by changing the chemical potential of each graphene layer. This can arbitrarily tailor the spatial distribution of the phase of the transmitted beam, providing mechanisms for active beam steering. Three different beam steerer (BS) designs are discussed: a graded-index (GRIN) graphene-based metamaterial block, an array of metallic waveguides filled with graphene-dielectric metamaterial and an array of planar waveguides created in a graphene-dielectric metamaterial block with a specific spatial profile of graphene sheets doping. The performances of the BSs are numerically analyzed, showing the tunability of the proposed designs for a wide range of output angles (up to approximately 70°). The proposed graphene-based tunable beam steering can be used in tunable transmitter/receiver modules for infrared imaging and sensing.

© 2016 Optical Society of America

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Abstract-Investigation of graphene assisted tunable terahertz metamaterials absorber

Xiaoyong He, Xu Zhong, Fangting Lin, and Wangzhou Shi
http://proxy.osapublishing.org/ome/abstract.cfm?uri=ome-6-2-331

By using the graphene-SiO2-Si-dielectrics-metallic ground plane (GSiO2SiDM) structures, we investigate the tunable properties of graphene metamaterials (MMs) absorbers in the terahertz region, including the effects of operation frequency, Fermi level, and graphene structure patterns. The results manifest that the graphene tunable GSiO2SiDM structure can achieve net absorption by changing structure parameters and the Fermi level of graphene layer. The resonant absorption and reflection curves of the GSiO2SiDM structures can be shifted in a wide range via controlling the applied electric fields. The modulation depth of resonant amplitude and frequency can reach more than 60% and 30%, respectively. The resonant peak (dip) of the absorption (reflection) curves shift to high frequency with the increase of Fermi level of the graphene layer. Due to broad absorption curve, the graphene MMs absorbers structures are suitable for the fabrication of broad absorber. The results are very useful to design novel devices, such as thermal detectors, imager, and biosensors.

© 2016 Optical Society of America

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