Abstract-High-precision digital terahertz phase manipulation within a multichannel field perturbation coding chip

 

Hongxin Zeng, Huajie Liang, Yaxin Zhang, Lan Wang, Shixiong Liang, Sen Gong, Zheng Li, Ziqiang Yang, Xilin Zhang, Feng Lan, Zhihong Feng, Yubin Gong, Ziqiang Yang, Daniel M. Mittleman

 

Fig. 1: MFPCC architecture and its high-precision terahertz phase manipulation function.

Fig. 2: Perturbation and phase shift of a single 2DEG-PMU with 0 and 1 states.

https://www.nature.com/articles/s41566-021-00851-6

Direct phase modulation is one of the most urgent and difficult issues in the terahertz research area. Here, we propose a new method employing a two-dimensional electron gas (2DEG) perturbation microstructure unit coupled to a transmission line to realize high-precision digital terahertz phase manipulation. We induce local perturbation resonances to manipulate the phase of guided terahertz waves. By controlling the electronic transport characteristics of the 2DEG using an external voltage, the strength of the perturbation can be manipulated, which affects the phase of the guided waves. This external control permits electronic manipulation of the phase of terahertz waves with high precision, as high as 2−5° in the frequency range 0.26–0.27 THz, with an average phase error of only 0.36°, corresponding to a timing error of only 4 fs. Critically, the average insertion loss is as low as 6.14 dB at 0.265 THz, with a low amplitude fluctuation of 0.5 dB, so the device offers near-ideal phase-only modulation.

Abstract-High-precision digital terahertz phase manipulation within a multichannel field perturbation coding 2DEG meta-chip

Hongxin Zeng, Huajie Liang, Yaxin Zhang, Ziqiang Yang, Feng Lan, Shixiong Liang, Zheng Li, Lan Wang, Xilin Zhang, Sen Gong, Yubin Gong, Ziqiang Yang, 

https://www.researchsquare.com/article/rs-92448/v1

Terahertz phase manipulation has always been based on direct coupling of the resonance of quasi-optical terahertz waves with metamaterials, which is accompanied by unnecessary amplitude modulation, thus limiting the accuracy of phase manipulation and its application in monolithic integrated systems. Here, we propose a coding meta-chip composed of transmission lines and two-dimensional electron gas (2DEG) meta-atoms, wherein local perturbation resonances are induced to manipulate the phase of terahertz waves. By controlling the electronic transport characteristics of the 2DEG with external voltages, the intensity of the perturbation can be manipulated, which affects the transmission phase of the waves. More importantly, the perturbation resonances induced by different meta-atoms can be coupled so that through digital coding of the perturbation state of 2DEG meta-atoms, the terahertz wave transmission phase can be manipulated with high precision. As a result, phase manipulation with different precisions from 2° to 5° is observed from 0.26 to 0.27 THz, where the average phase error is only 0.36°, and the maximum root mean square of the transmittance is 0.36 dB. This high-precision phase manipulation via field coding has great application potential in the fields of beamforming, wireless communication, and high-resolution imaging.

Abstract-High-speed efficient terahertz modulation based on tunable collective-individual state conversion within an active 3nm-two dimensional electron gas metasurface

Yuncheng Zhao, Lan Wang, Yaxin Zhang, Shen Qiao, Shixiong Liang, Xilin Zhang, Xiaoqing Guo, Zhihong Feng, Feng Lan, Zhi Chen, Xiaobo Yang, Ziqiang Yang,

https://pubs.acs.org/doi/abs/10.1021/acs.nanolett.9b01273#

Terahertz (THz) modulators are always realized by dynamically manipulating the conversion between different resonant modes within a single unit cell of an active metasurface. In this paper, to achieve real high-speed THz modulation, we present a staggered netlike two-dimensional electron gas (2DEG) nanostructure composite metasurface that has two states: a collective state with massive surface resonant characteristics and an individual state with meta-atom resonant characteristics. By controlling the electron transport of the nanoscale 2DEG with an electrical grid, collective-individual state conversion can be realized in this composite metasurface. Unlike traditional resonant mode conversion confined in meta-units, this state conversion enables the resonant modes to be flexibly distributed throughout the metasurface, leading to a frequency shift of nearly 99% in both the simulated and experimental transmission spectra. Moreover, such a mechanism can effectively suppress parasitic modes and significantly reduce the capacitance of the metasurface. Thereby, this composite metasurface can efficiently control the transmission characteristics of THz waves with high-speed modulations. As a result, 93% modulation depth is observed in the static experiment and modulated sinusoidal signals up to 3 GHz are achieved in the dynamic experiment while the -3dB bandwidth can reach up to 1GHz. This tunable collective-individual state conversion may have great application potential in wireless communication and coded imaging.

Abstract-Dual-band refractometric terahertz biosensing with intense wave-matter-overlap microfluidic channel

Feng Lan, Feng Luo, Pinaki Mazumder, Ziqiang Yang, Lin Meng, Zhengqiang Bao, Jun Zhou, Yaxin Zhang, Shixiong Liang, Zongjun Shi, Abdur Rauf Khan, Ziqi Zhang, Luyang Wang, Jing Yin, and Hongxin Zeng

Fig. 1 (a) Schematic diagram of the microfluidic sensor, (b) microscopic image of the meta-atoms, (c) resonant unit.

https://www.osapublishing.org/boe/fulltext.cfm?uri=boe-10-8-3789&id=415013

We theoretically and experimentally demonstrate a label-free terahertz biosensor with ultrahigh sensitivity and distinctive discretion. By constructing a metal-air-metal (MAM) metamaterial perfect absorber (MPA) with a metallic paired-ring resonator array, a hollow microfluidic channel, and a backed reflector, a novel dual-band absorptive sensing platform is proposed in the THz range. The near field coupling by dipole-induced trapped modes and the magnetic momentum caused a vertical to transverse power flux that dramatically enhanced the electromagnetic field on top of the metasurface and in the microfluidic channel, respectively. Both the resonant modes exhibit perfect absorption and produce ultrahigh normalized sensitivities of 0.47/RIU (refractive index unit, RIU) and 0.51/RIU at 0.76 THz and 1.28 THz, respectively. Compared with conventional microfluidic sensors, the salient advantages of our design are the perfect spatial overlap for light-matter interaction and polarization insensitivity. Characterized by THz time domain spectroscopic absorption quantification measurements with different concentrations of bovine serum albumin (BSA), the proposed sensor exhibits promising applications in microfluidic biosensing.

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

Abstract-A Review of THz Modulators with Dynamic Tunable Metasurfaces

Lan Wang,  Yaxin Zhang , Xiaoqing Guo, Ting Chen, Huajie Liang,  Xiaolin Hao,  Xu Hou, Wei Kou,  Yuncheng Zhao,  Tianchi Zhou,  Shixiong Liang, Ziqiang Yang

https://www.mdpi.com/2079-4991/9/7/965/htm

Terahertz (THz) radiation has received much attention during the past few decades for its potential applications in various fields, such as spectroscopy, imaging, and wireless communications. To use terahertz waves for data transmission in different application systems, the efficient and rapid modulation of terahertz waves is required and has become an in-depth research topic. Since the turn of the century, research on metasurfaces has rapidly developed, and the scope of novel functions and operating frequency ranges has been substantially expanded, especially in the terahertz range. The combination of metasurfaces and semiconductors has facilitated both new opportunities for the development of dynamic THz functional devices and significant achievements in THz modulators. This paper provides an overview of THz modulators based on different kinds of dynamic tunable metasurfaces combined with semiconductors, two-dimensional electron gas heterostructures, superconductors, phase-transition materials, graphene, and other 2D material. Based on the overview, a brief discussion with perspectives will be presented. We hope that this review will help more researchers learn about the recent developments and challenges of THz modulators and contribute to this field.

Abstract-Terahertz Radiation from Combined Metallic Slit Arrays

Dazhi Li, Makoto Nakajima, Masahiko Tani, Jinfeng Yang, Hideaki Kitahara, Masaki Hashida, Makoto Asakawa, Wenxin Liu, Yanyu Wei,  Ziqiang Yang,

https://www.nature.com/articles/s41598-019-43072-2

We report an approach to efficiently generate terahertz radiation from a combined periodic structure. The proposed configuration is composed of two metallic slit arrays deliberately designed with different periodic length, slit width and depth. We found that the combination of the two slit arrays could provide special electromagnetic modes, which exhibit nonradiative property above the surface of one slit array and radiative property inside the other one. An electron beam holding proper energy could resonate with those modes to generate strong and directional electromagnetic radiations in the terahertz regime, indicating that the approach has the potential in developing high-performance terahertz radiation sources.

Abstract-The Influence on the Q Value of the THz Meta-surface From the Tip Charge Accumulation Coupling

Han Sun,  Lan Wang, Yaxin Zhang, Feng Lan, Shixiong Liang, Kang Xue, Ziqiang Yang,

https://ieeexplore.ieee.org/document/8691625

With the adventure of metamaterials, there has been a tremendous advancement in the manipulation of the terahertz (THz) wave. However, the excitation of high-Q-factor resonance has been a great challenge in traditional metamaterials due to the ohmic and radiation losses. In this paper, the influence of the tip charge accumulation effect on the high-Q value meta-surface has been studied within the triangular array meta-surface. It is found that when the tip charges accumulation resonance from each pair of triangular units can couple with each other to construct a significant resonant mode which could trap more energy to achieve higher Q value. Moreover, the stacking of the induced charges distributed at the surface of the meta-unit making the coupling strength is further increased so that the strong tip charge accumulation effect could also affect the Q-value. The experiment verified this phenomenon, which shows the stronger coupling resonance and tip charges accumulation could result in the enhancement of the Q-value. This research has potential applications in high-Q THz devices.

Abstract-Dynamic Photoinduced Controlling of the Large Phase Shift of Terahertz Waves via Vanadium Dioxide Coupling Nanostructures

Yuncheng Zhao, Yaxin Zhang, Qiwu Shi, Shixiong Liang,  Wanxia Huang,  Wei Kou,  Ziqiang Yang,

https://pubs.acs.org/doi/10.1021/acsphotonics.8b00276

Utilizing terahertz (THz) waves to transmit data for communication and imaging places high demands on phase modulation. However, until now, it is difficult to realize a more than 100° phase shift in the transmission mode with one-layer structure. In this paper, a ring-dumbbell composite resonator nested with VO2 nanostructures is proposed to achieve the large phase shift. It is found that in this structure a hybrid mode with an enhanced resonant intensity, which is coupled by the L-C resonance and dipole resonance has been observed. Applying the photoinduced phase transition characteristics of VO2, the resonant intensity of the mode can be dynamically controlled, which leads to a large phase shift in the incident THz wave. The dynamic experimental results show that controlling the power of the external laser can achieve a phase shift of up to 138° near 0.6 THz using this one-layer VO2 nested composite structure. Moreover, within a 55 GHz (575–630 GHz) bandwidth, the phase shift exceeds 130°. This attractive phase shift modulation may provide prospective applications in THz imaging, communications, and so on.

Abstract-Ultrasensitive dual-band terahertz sensing with metamaterial perfect absorber

Weihao Zhang,   Feng Lan,  Jinyang Xuan,   Pinanki Mazumder,  Mahdi Aghadjani,  Ziqiang Yang,  Lin Men

https://ieeexplore.ieee.org/document/8247404/

Due to the weak energy storage characteristics of the monolayer metamaterial, how to increase the sub-wavelength scale interaction between biological or chemical samples and terahertz wave on sufficient sensitivity premise becomes the key scientific problems in the study of terahertz sensing technology. In this paper, an ultrasensitive dual-band spectral terahertz sensor with polarization insensitive metamaterial perfect absorber (MPA) is demonstrated. A double-ring shaped metal microstructure integrated with microfluidic channel is applied in the polarization sensitive terahertz sensor. The numerical results show that the normalized sensitivity of refractive index unit 0.638/RIU with mode A and 0.582/RIU with mode B are obtained at 1.04THz and 0.506THz, respectively. The absorptive sensing mechanism is elucidated by the electric field and surface current distributions. Compared to other metamaterials (MMs) based terahertz sensors, the proposed MPA sensor with significantly confined field, enhanced sensitivity and polarization insensitivity is much more suitable for label-free terahertz probing of fluidic matter detection.

Abstract-Linear polarization conversion of transmitted terahertz wave with double-layer meta-grating surfaces

Han Sun, Yaxin Zhang, Kailong Wang, Yuncheng Zhao, Wei Kou, Shixiong Liang, Jiaguang Han, and Ziqiang Yang

https://www.osapublishing.org/col/abstract.cfm?uri=col-16-8-081601

In this Letter, we demonstrate a linear polarization conversion of transmitted terahertz wave with double-layer meta-grating surfaces, which integrated the frequency selectivity of a split ring resonator metasurface and the polarization selectivity of a metallic grating surface. Since the double-layer can reduce the loss, and the Fabry–Perot like resonant effect between the two layers can improve the conversion efficiency, this converter can rotate the incident y-polarized terahertz wave into an x-polarized transmitted wave with relatively low loss and high efficiency. Experimental results show that an average conversion efficiency exceeding 75% from 0.25 to 0.65 THz with the highest efficiency of 90% at 0.43 THz with only −2  dB loss has been achieved.

© 2018 Chinese Laser Press

Abstract-Dynamic Photo-induced Controlling of the Large Phase Shift of Terahertz Waves via Vanadium Dioxide Coupling Nanostructures

Yuncheng Zhao, Yaxin Zhang, Qiwu Shi, Shixiong Liang, Wanxia Huang, Wei Kou, Ziqiang Yang,

https://pubs.acs.org/doi/abs/10.1021/acsphotonics.8b00276?mi=aayia761&af=R&AllField=nano&target=default&targetTab=std

Utilizing terahertz (THz) waves to transmit data for communication and imaging places high demands on phase modulation. However, until now, realizing a large phase shift using a one-layer structure in transmission mode has been difficult. In this paper, utilizing a composite unit cell by coupling the traditional metallic wire dipolar resonance and the split-ring capacitive inductance resonance results in an enhanced resonance coupling mode. Combined with a vanadium dioxide (VO2) nanostructure and applying the photo-induced phase transition, the resonant intensity of the mode can be dynamically controlled, which leads to an ultralarge phase shift in the incident THz wave. The dynamic experimental results show that controlling the power of the external laser can achieve a phase shift of up to 138 degrees near 0.6 THz using this one-layer VO2 nested composite structure. Moreover, within a 55 GHz (575 GHz-630 GHz) bandwidth, the phase shift exceeds 130 degrees. This attractive phase shift modulation may provide prospective applications in THz imaging, communications, etc.

Abstract-Enhanced quadruple-resonant terahertz metamaterial with asymmetric hybrid resonators

Minglei Shi, Feng Lan, Pinaki Mazumder, Mahdi Aghadjani, Ziqiang Yang, Lin Meng, Jun Zhou,

https://www.sciencedirect.com/science/article/pii/S0925346717306997

This paper presents the design, fabrication and investigation of a quadruple-resonant terahertz metamaterial that comprises two different Electric-inductance capacitance (ELC) resonators in a vertical configuration. Owing to asymmetric electric field coupling between the two resonators, the combined structure exhibits better performance in terms of transmission minima and bandwidths than the individual particles. The distributions of the surface current and electric field reveal quasi-quadrupole resonance, electric dipolar resonance and coupling between these resonances at different resonant frequencies. Moreover, the resonant frequencies are tunable by adjusting the corresponding geometrical parameters. Above all, the excellent performance of the proposed structure makes it promising for application in multiband terahertz devices.

Abstract-Coherent Terahertz Radiation from Multiple Electron Beams Excitation within a Plasmonic Crystal-like structure

• Yaxin Zhang
• , Yucong Zhou
• , Yin Gang
• , Guili Jiang
•  & Ziqiang Yang

http://www.nature.com/articles/srep41116

Coherent terahertz radiation from multiple electron beams excitation within a plasmonic crystal-like structure (a three-dimensional holes array) which is composed of multiple stacked layers with 3 × 3 subwavelength holes array has been proposed in this paper. It has been found that in the structure the electromagnetic fields in each hole can be coupled with one another to construct a composite mode with strong field intensity. Therefore, the multiple electron beams injection can excite and efficiently interact with such mode. Meanwhile, the coupling among the electron beams is taken place during the interaction so that a very strong coherent terahertz radiation with high electron conversion efficiency can be generated. Furthermore, due to the coupling, the starting current density of this mechanism is much lower than that of traditional electron beam-driven terahertz sources. This multi-beam radiation system may provide a favorable way to combine photonics structure with electronics excitation to generate middle, high power terahertz radiation.

Abstract-Mode coupling in terahertz metamaterials using sub-radiative and super-radiative resonators

Shen Qiao¹, Yaxin Zhang^1,a), Yuncheng Zhao¹, Shixiong Liang², Gaiqi Xu¹, Han Sun¹ and Ziqiang Yang¹
http://scitation.aip.org/content/aip/journal/jap/118/19/10.1063/1.4936169?TRACK=RSS
a) Author to whom correspondence should be addressed. Electronic mail:Zhangyaxin@uestc.edu.cn
J. Appl. Phys. 118, 193104 (2015); http://dx.doi.org/10.1063/1.4936169

We theoretically and experimentally explored the electromagnetically induced transparency (EIT) mode-coupling in terahertz (THz) metamaterialresonators, in which a dipole resonatorwith a super-radiative mode is coupled to an inductance-capacitance resonator with a sub-radiative mode. The interference between these two resonators depends on the relative spacing between them, resulting in a tunable transparency window in the absorptionspectrum.Mode coupling was experimentally demonstrated for three spacing dependent EITmetamaterials. Transmittance of the transparency windows could be either enhanced or suppressed, producing different spectral linewidths. These spacing dependent mode-couplingmetamaterials provide alternative ways to create THz devices, such as filters, absorbers, modulators, sensors, and slow-light devices.

Abstract-Gbps terahertz external modulator based on a composite metamaterial with a double-channel heterostructure

Yaxin Zhang , Shen Qiao , Shixiong Liang , Zhenhua Wu , Ziqiang Yang , Zhihong Feng , Han Sun , Yucong Zhou , Linlin Sun , Zhi Chen , Xianbing Zou , Bo Zhang , Jianhao Hu , Shaoqian Li ,Qin Chen , Ling Li , Gaiqi Xu , Yuncheng Zhao , and Shenggang Liu

Nano Lett., Just Accepted Manuscript

DOI: 10.1021/acs.nanolett.5b00869

Publication Date (Web): April 28, 2015

Copyright © 2015 American Chemical Society

http://pubs.acs.org/doi/abs/10.1021/acs.nanolett.5b00869

The past few decades have witnessed a substantial increase in terahertz (THz) research. Utilizing THz waves to transmit communication and imaging data has created a high demand for phase and amplitude modulation. However, current active THz devices, including modulators and switches, still cannot meet THz system demands. Double-channel heterostructures, an alternative semiconductor system, can support nano-scale two-dimensional electron gases (2DEGs) with high carrier concentration and mobility and provide a new way to develop active THz devices. In this article, we present a composite metamaterial structure that combines an equivalent collective dipolar array with a double-channel heterostructure to obtain an effective, ultra-fast and all-electronic grid-controlled THz modulator. Electrical control allows for resonant mode conversion between two different dipolar resonances in the active device, which significantly improves the modulation speed and depth. This THz modulator is the first to achieve a 1-GHz modulation speed and 85% modulation depth during real-time dynamic tests. Moreover, a 1.19-rad phase shift was realized. A wireless free-space-modulation THz communication system based on this external THz modulator was tested using 0.2-Gbps eye patterns. Therefore, this active composite metamaterial modulator provides a basis for the development of effective and ultra-fast dynamic devices for THz wireless communication and imaging systems.

Abstract-Controlling the transparency window in terahertz band using mode coupling metamaterials

Shen Qiao¹, Yaxin Zhang^1,a), Gaiqi Xu¹, Linlin Sun¹, Han Sun¹, Ling Li¹,Shixiong Liang², Yuncheng Zhao¹ and Ziqiang Yang¹
http://scitation.aip.org/content/aip/journal/jap/117/6/10.1063/1.4907870
1 Terahertz Science Cooperative Innovation Center, University of Electronic Science and Technology of China, Chengdu 610054, China
2 National Key Laboratory of Application Specific Integrated Circuit, Hebei Semiconductor Research Institute, Shijiazhuang 050051, China
a) Author to whom correspondence should be addressed. Electronic mail: Zhangyaxin@uestc.edu.cn
J. Appl. Phys. 117, 063103 (2015); http://dx.doi.org/10.1063/1.4907870

Mode-coupling metamaterials are typically composite structures with different resonance modes. Controlling couplings among these modes results in a sharp transparency window within the absorption spectrum of the metamaterials. Here, we present a composite structure of ring and split-ring resonators to constitute a new structure with entirely new mode. Experimental results show that the asymmetric combination of these resonators can result in a variation in transparency strength. The dimensions and relative positions of the split-ringresonator are discussed particularly with a series of experimental results. Simulation results show that the coupling intensity is the main reason for this behavior. Exploiting this aspect, a way to control the transparency window between composite structure metamaterials is proposed.

Abstract-Photoinduced active terahertz metamaterials with nanostructured vanadium dioxide film deposited by sol-gel method

Yaxin Zhang, Shen Qiao, Linlin Sun, Qi Wu Shi, Wanxia Huang, Ling Li, and Ziqiang Yang  »View Author Affiliations

Optics Express, Vol. 22, Issue 9, pp. 11070-11078 (2014)
http://dx.doi.org/10.1364/OE.22.011070

Applying the photoexcitation characteristics of vanadium dioxide (VO₂), a dynamic resonant terahertz (THz) functional device with the combination of VO₂ film and dual-resonance metamaterial was suggested to realize the ultrafast external spatial THz wave active manipulation. The designed metamaterial realizes a pass band at 0.28–0.36 THz between the dual-resonant frequencies, and the VO₂ film is applied to control the transmittance of the spatial THz wave. More than an 80% modulation depth has been observed in the statics experiment, and the dynamic experimental results illustrate that this active metamaterial realizes up to a 1 MHz amplitude modulation signal loaded on a 0.34 THz carrier wave without any low noise amplified devices. The electromagnetic properties and photoinduced dynamic characteristics of this structure may have many potential applications in THz functional components, including modulators, intelligent switches, and sensors.

© 2014 Optical Society of America

Abstract-Terahertz dual-resonance bandpass filter using bilayer reformative complementary metamaterial structures

Feng Lan, Ziqiang Yang, Limei Qi, Xi Gao, and Zongjun Shi  »View Author Affiliations

Optics Letters, Vol. 39, Issue 7, pp. 1709-1712 (2014)
http://dx.doi.org/10.1364/OL.39.001709

http://www.opticsinfobase.org/ol/abstract.cfm?uri=ol-39-7-1709

A dual-resonance frequency selective surface filter in the THz range that uses bilayer modified complementary metamaterial structures is proposed in this Letter. The bandpass filter, with dual bands centered at 0.315 and 0.48 THz, uses a single crystal quartz substrate and is simulated, fabricated, and measured. To minimize the manufacturing risks of working with fragile and thin quartz substrates, efforts have been made to improve the transmission frequency response features at realizable substrate thicknesses. Experimental results from 0.1 to 0.6 THz measured by THz time-domain spectroscopy show excellent agreement with the simulation results.

© 2014 Optical Society of America