Abstract-Multi-mode graphene based terahertz amplitude modulation enhanced by hollow cross H-structured metasurface

Liangping Xia, Yixuan Zou, Man Zhan,Wenjuan Yan, Suihu Dang, Songbai Li, Shaoyun Yin,  Hongliang Cui

https://iopscience.iop.org/article/10.1088/1402-4896/ab1bfe/pdf

A graphene-metasurface based THz amplitude modulator enhanced with the hollow cross H array in a metal film is proposed. Based on the transmission line theory, the equivalent analysis model of the modulator is built. With the model, the multi-mode resonation excited by the metasurface is analyzed and the amplitude modulations of the THz transmission are discussed. By applying modulation voltage between the metallic metasurface and graphene film in the experiment, three enhanced modes in the transmission spectrum are observed and the maximum modulation depth is enhanced to 49.3% in the band of 0.1-1.8THz. The experimental results exhibit a good agreement with the theory analysis.

Abstract-Multi-mode graphene based terahertz amplitude modulation enhanced by hollow cross H-structured metasurface

Physica Scripta

Liangping Xia, Yixuan Zou, Man Zhang, Wenjuan Yan, Suihu Dang, Songbai Li, Shaoyun Yin,  Hongliang Cui

https://iopscience.iop.org/article/10.1088/1402-4896/ab1bfe/pdf

A graphene-metasurface based THz amplitude modulator enhanced with the hollow cross H array in a metal film is proposed. Based on the transmission line theory, the equivalent analysis model of the modulator is built. With the model, the multi-mode resonation excited by the metasurface is analyzed and the amplitude modulations of the THz transmission are discussed. By applying modulation voltage between the metallic metasurface and graphene film in the experiment, three enhanced modes in the transmission spectrum are observed and the maximum modulation depth is enhanced to 49.3% in the band of 0.1-1.8THz. The experimental results exhibit a good agreement with the theory analysis.

Abstract-Deep Electrical Modulation of Terahertz Wave Based on Hybrid Metamaterial-Dielectric-Graphene Structure

Liangping Xia, Xin Zhang, Man Zhang, Suihu Dang, Shijian Huang, Yong Tan, Wenjuan Yan, Hong-Liang Cui

https://www.mdpi.com/2076-3417/9/3/507

A terahertz modulation structure based on hybrid metamaterial and graphene is proposed and demonstrated in this work. The metamaterial with a square slit ring array excites terahertz resonance in the slits and enhances the interaction between the terahertz wave and graphene. The graphene layer acting as the active material is tuned by the applied electrical field. With the separation by a dielectric layer between the graphene and the metallic structure, the resonant frequency and transmitted energy are both modulated by the graphene. Experimental result indicates that the modulation depth of the terahertz transmitted amplitude is 65.1% when the applied modulation voltage is tuned 5 V.

Abstract-Low loss terahertz devices based on polymer substrate

Liangping Xia, Hongyan Mao, Xinqun Zhang, Suihu Dang, Wenjuan Yan, Songbai Li,

https://www.spiedigitallibrary.org/conference-proceedings-of-spie/10848/1084808/Low-loss-terahertz-devices-based-on-polymer-substrate/10.1117/12.2505147.short?SSO=1

The fabrication method of hard template substrate supporting in the lithography process is proposed to realize THz devices based on low loss polymer substrate with large effective area. Based on this method, the THz polarizer with single layered and double layered grating structure are fabricated and measured. The transmission spectra indicates that the loss of the polarizer is low and the polarization extinction ratio is as high as 55dB and 70dB for single and double layered samples respectively. The THz band stop filter result indicates that the loss keeps low and the filter band width is wider for the multi-layered metallic structure.

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Abstract- Graphene Terahertz Amplitude Modulation Enhanced by Square Ring Resonant Structure

 Liangping Xia,  Xin Zhang, Dongshan Wei. Hong-Liang Cui, Chunlei Du

http://ieeexplore.ieee.org/document/8141872/

A terahertz amplitude modulator based on graphene on a metallic square ring resonant structure is proposed. By separating the graphene and the metallic structure with a thin organic dielectric layer, both the resonant frequency and the amplitude of the transmission resonant peak are modulated when graphene is electrically tuned by a bias voltage. A maximal amplitude modulation depth of 72% at the frequency of 0.6 THz is achieved for the fabricated Terahertz modulator. An analysis model based on the transmission line theory is built to explore the modulation mechanism. Results of the transmission spectrum and the amplitude modulation indicate a good agreement between the transmission line theoretical predictions and the experimental measurements

Abstract-Detection of DNA oligonucleotides with base mutations by terahertz spectroscopy and microstructures

Mingjie Tang,  Mingkun Zhang, Shihan Yan,  Liangping Xia, Zhongbo Yang, Chunlei Du, Hong-Liang Cui, Dongshan Wei,

http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0191515

DNA oligonucleotides with a 5-base mutation at the 3'-terminus were investigated by terahertz (THz) spectroscopy in a marker-free manner. The four single-stranded oligonucleotides with 17nt have been detected with specificity on a microfluidic chip, and corroborated by spectral measurements with split-ring resonators. The number of hydrogen bonds formed between the oligonucleotide and its surrounding water molecules, deemed a key contribution to the THz absorption of biological solutions, was explored by molecular dynamics simulations to explain the experimental findings. Our work underlies the feasibility of THz spectroscopy combined with microstructures for marker-free detection of DNA, which may form the basis of a prospective diagnostic tool for studying genic mutation.

Abstract-Cell viability and hydration assay based on metamaterial-enhanced terahertz spectroscopy

Yu Liu,  Mingjie Tang,  Liangping Xia,  Wenjing Yu,  Jia Peng, Yang Zhang,  Marc Lamy de la Chapelle,  Ke Yang,  Hong-Liang Cui,  Weiling Fu

http://pubs.rsc.org/en/content/articlelanding/2017/ra/c7ra09609g#!divAbstract

As a fast-growing technology, terahertz time-domain spectroscopy (THz-TDS) is becoming increasingly pervasive in biological applications, targeting a range of biomaterials from biomolecules to tissues. However, THz-TDS studies at the cellular level are quite limited. Thus, a study to analyze the living state and hydration state of a tumor cell in a label-free manner is carried out and reported here. Combined with a specially designed THz metamaterial, a tumor cell monolayer was detected continuously over a period of time. In addition, in order to explore the possible impact of the metamaterial on tumor cells, the secretion of IL-6, IL-8, GM-CSF and GROα of cell supernatants was detected. The results demonstrated that the technology could characterize the living state by monitoring the extracellular water and investigate the hydration state inside a tumor cell in real time, showing great application potential for the label-free detection of normal cells and tumor cells of diverse malignant degree.