Abstract-Optical control of terahertz plasmon-induced transparency based on hybrid CsPbBr3 quantum dot metasurfaces

Yue Yang, Jining Li, Jie Li, Jin Huang, Qingyan Li, Yating Zhang, Haitao Dai, and Jianquan Yao

(a) Schematic illustration of the CsPbBr3 QDs based PIT structure. (b) Optical microscopy of the designed metasurface. (c) Design dimensions of a unit cell. (d) PL intensity and absorption spectrum of CsPbBr3 QDs. The inset shows the TEM image of the synthesized QDs. (e) Measured transmission spectra of the PIT structure with and without spin-coating PEDOT: PSS/ CsPbBr3 QDs.

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-28-16-24047

Incorporating photosensitive material into structured metamaterials explores opportunities for dynamical operation across the terahertz functional devices, enabled by the efficient interaction between light and matter. In this work, the CsPbBr3 quantum dots are incorporated into the metasurfaces, realizing the active control of the plasmon-induced transparency. In the experiment, the normalized modulation depth of transparency effect is up to 74%. Rigorous numerical and theoretical simulations verify that the variation of dynamic physical process is associated with the charge storage capacity in the capacitive metasurface. An observed phase advance and group delay indicate the hybrid metasurface is useful for slow light application. In addition, the simple process provides a convenient way for the development of terahertz functional devices.

© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Active bidirectionally controlled terahertz interference fringe shift in DMSO-doped PEDOT:PSS film

Applied Physics Letters

Jingyu Liu, Bin Liu, Dandan Liu, Luyao Xiong, Jingling Shena, Bo Jingyu Liu, Bin Liu, Dandan Liu, Luyao Xiong, Jingling Shena,  Bo Zhanga

https://aip.scitation.org/doi/abs/10.1063/5.0011845

An active bidirectionally controlled terahertz interference fringe shift in a dimethyl sulfoxide (DMSO)-doped poly(3,4-ethylenedioxythiophene):poly(4-styrenesulfonate) (PEDOT:PSS) film structure was investigated. An interference phenomenon that occurred as a result of wavefront segmentation in a THz time-domain spectroscopy (THz-TDS) system was observed. This THz interference fringe spectrum can be modulated bidirectionally through application of a bias voltage and laser irradiation in terms of its both THz amplitude and interference fringe peaks. The refractive index of the film has an effect on the frequency domain and causes both optical path enhancement and a change in the interference period. THz interference fringes with an electrically induced blueshift and with a photo-induced redshift were acquired.

A life with terahertz waves

A fascination with electromagnetic waves at the boundary between light and radio waves

A prototype of the integrated terahertz radar. © Yasuaki Monnai, Keio University

https://research-highlights.keio.ac.jp/2020/07/a.html?fbclid=IwAR2B9o9ScG8k6U-Lpjdw98NcQZ8-hZ91KjYQ48WQ9-pC5LgMrQfiDle7OOA

First encounters with terahertz waves

"My doctoral research was on controlling beams of terahertz radiation," says Yasuaki Monnai, an associate professor at Keio University's Department of Applied Physics and Physico-Informatics. "We were working at the boundary between light and radio waves. Most likely, what led me to follow this path was meeting a professor who was transmitting electric power wirelessly using microwaves. I was impressed by his ideas and methodology, which eventually led to my interest in terahertz waves, waves that have higher frequencies than microwaves."

Monnai adds that research on light and radio waves evolved as separate fields, with few technological advances at the boundaries of these waves. Furthermore, radio waves are generated by oscillator circuits and transmitted using antennae, but light is generated by lasers and transmitted using lens systems.

Although the terahertz frequency band has the potential for communication speeds much higher than the best of today's Wi-Fi, enabling instant downloads of high-definition images, one of the issues to overcome is preventing the divergence of terahertz beams. "For example, infrared remote TV-controllers are highly directional and if they are pointed slightly away from the target, they fail to work," explains Monnai. "For my doctorate, I proposed a device to control the directionality of terahertz beams and demonstrated its principle of action. I had to visit a group in Germany to complete my research because my laboratory in Japan did not have the highly specialized terahertz wave equipment required."

Studying in Germany and the verbalization of ideas

Monnai's memories of his stay in Germany include how students approached their research and job hunting. "In Japan, it is assumed that all students work along the same timeline towards important events such as completing doctoral programs and finding jobs," says Monnai. "But in Germany, I saw that it was a case of 'people acting once they were prepared,' which means the timing for these events depends on the individual's circumstances. People take their time to think about their future without external timing constraints. This is in total contrast to the situation faced by students in Japan who all try to graduate and get jobs to start on the 1st of April of that fiscal year."

Monnai recalls being impressed by the ability of the German students to clearly explain their intentions in words. "I have heard that in physics exams, students are expected to not only solve equations but also answer questions verbally," explains Monnai. "On TV programs for children, I noticed it was common for ordinary children to explain in their own words not only what they wanted to be in the future, but also why. I felt that this kind of culture was the basis for the 'verbalization of ideas.'"

Focus on terahertz waves and remote heartbeat detection

There are a wide range of applications of electromagnetic waves. For example, microwaves are used for heating meals, infrared rays for monitoring temperature, and X-rays for looking inside matter. However, there is increasing interest in the unexplored terahertz wavelengths. "One of my research themes is focused on terahertz radar with the goal of controlling machines and supporting human cognitive behavior," explains Monnai. "We recently developed a compact, highly penetrating, high-resolution terahertz radar system for application in the fields of mobile/wearable devices and drones. We revealed the power of our technology by demonstrating non-contact and remote detection of human heartbeats where the terahertz radiation penetrated a person's clothes."

Demonstration of non-contact heartbeat detection using a terahertz radar. © Yasuaki Monnai, Keio University

The terahertz frequency band is generally recognized as covering the range from approximately 0.3 THz to around 10 THz, where 'tera' refers to one trillion (1012) cycles per second. This corresponds to the relatively long wavelengths of 1 mm to 0.1 mm when compared to around 500 nm (10-9m) for visible light. Notably, terahertz radiation is noninvasive and not harmful to the human body, thereby offering a wide range of applications ranging from inspecting defects in industrial products to whole body scanners at airports and cancer detection.

Monnai explains that the resolution of terahertz waves is significantly higher than conventional microwaves and millimeter waves, and media are more transparent to terahertz radiation than light enabling better detection. He adds that his group's technology does not require phase shifters, lenses, mechanical scanners, or other such components, thereby enabling a highly compact system without moving parts.

Terahertz waves as data interfaces between the physical world and information technology

It is becoming increasingly clear that the unique properties of terahertz waves have the potential to be extremely useful not only as communications carriers but also as measurement probes.

"Terahertz waves is a next generation technology acting as the interface for incorporating data in the physical world into the cyber world, such as autonomous driving and telepresence," says Monnai. "I believe that we must combine cutting-edge hardware and software for such applications. So currently, I am focusing my research on terahertz systems with smart hardware."

Abstract-Simulation of a highly birefringent photonic crystal fiber in terahertz frequency region

Md. Ekhlasur Rahaman, Himadri Shekhar Mondal, Md. Bellal Hossain, Md. Mahbub Hossain, Md. Shamim Ahsan, Rekha Saha

https://link.springer.com/article/10.1007/s42452-020-03210-2

We have designed a Photonic Crystal Fiber (PCF) to achieve high birefringence optical property in the terahertz (THz) frequency region. Air holes look like rectangular shape in cladding area and elliptical air hole in the center zone are considered for the proposed PCF. To identify loss characteristics of the proposed PCF, effective material loss (EML) and confinement loss also have been studied in this paper. The commercial optical properties analyzer, COMSOL Multiphysics 5.3a software has been used for numerical analysis of the designed PCF. To obtain the optimal PCF structure properties, we have varied the elliptical shaped air holes major axis length and adjacent ellipse pitch distance. Numerical analysis shows the maximum birefringence of 0.0921 and minimum confinement loss of 1.36×10−4 cm−1$1.36\times {10}^{-4}{\text{cm}}^{-1}$ for the proposed PCF. We hope that this highly birefringent PCF will contribute in the field of polarization filter, bio-sensing and terahertz communication devices.

Abstract-Waveguiding characteristics of a metal-clad dielectric grating for terahertz applications

Ali Tehranian, Mehdi Ahmadi-Boroujeni, Afshin Abbaszadeh,

https://www.sciencedirect.com/science/article/abs/pii/S003040182030732X

Dielectric gratings (DGs) have recently been introduced as a new platform for guiding dielectric-based geometrically-induced surface plasmons (SPs) called spoof SPs (SSPs). In this paper, we report on the modal analysis of a metal-clad DG waveguide and compare its performance with other counterparts including the dielectric image guide (IG) and the metal grating (MG) waveguide. The proposed DG waveguide is made up of a periodic array of high-resistivity silicon (HR-Si) pillars on a metal plate with a metal cladding at a proper distance above the structure. By modal analysis of 2D and 3D structures, we show that the presence of the metal cladding enhances the modal field confinement without sacrificing the bandwidth. In addition, modal characteristics of the structure at hand in the presence of a thin substrate are studied. It is found that the lateral field confinement and bending loss can be impaired in the presence of a substrate. We also study the shape of dielectric pillars and show that nearly the same performance can be achieved by cubic and cylindrical pillars. Finally, some waveguide devices such as a bend, a directional coupler, and a ring resonator are also implemented and studied to assess the applicability of the proposed metal-clad DG waveguide.

Abstract-Terahertz Inspection of Buildings and Architectural Art

Kirsti Krügener,  Jan Ornik,  Lorentz M. Schneider, Alexander Jäckel, Corinna L. Koch-Dandolo,  Enrique Castro-Camus, Nicole Riedl-Siedow, Martin Koch, Wolfgang Viöl

https://www.mdpi.com/2076-3417/10/15/5166

We present a broad literature review on the uses of terahertz radiation for the inspection architectural art, as well as building structures. As an example of the uses of terahertz in this field, we also include original results on a non-destructive assessment of a conservation intervention on murals of the Konstantinbasilika in Trier, Germany while using terahertz time-of-flight spectroscopy.

An Ultra-Thin Terahertz Metalens

Illustration of a terahertz metasurface ultra-thin collimator for power enhancement. (T. Suzuki, TUAT)

https://www.photonicsviews.com/an-ultra-thin-terahertz-metalens/

Terahertz radiation has barely been exploited compared to most of the rest of the electro­magnetic spectrum. Yet T-rays potentially have appli­cations in next-generation wireless communi­cations (6G/7G), security systems, biome­dicine, and even art history. A new device for controlling T-rays using a specially designed meta­surface with properties not found in nature could begin to realize this potential.

Terahertz technology that allows gene­ration, detection, and appli­cation of terahertz waves has taken off in the last decade or so, closing the terahertz gap somewhat. But the performance and dimensions of conventional optical components able to mani­pulate terahertz waves have not kept up with this rapid development. One reason is the lack of naturally occurring materials suitable for the terahertz waveband. However, researchers at Tokyo Uni­versity of Agriculture and Techno­logy (TUAT) led by terahertz wave engineer Takehito Suzuki have recently developed an optical component that can more easily mani­pulate T-rays and in a practical fashion by using a material that doesn’t occur in nature.

Conventionally, a colli­mator, typically consisting of a curved lens or mirror, can mani­pulate T-rays is a bulky three-dimensional structure made of naturally occurring materials. But the researchers Takehito Suzuki, Kota Endo, and Satoshi Kondoh, have devised a collimator as an ultra-thin (2.22 micro­meters) plane made from a meta­surface. These properties come not from whatever metal or plastic base substance they are composed of, but instead from the geometry and arrangement of the material in tiny repeating patterns that can bend electro­magnetic waves in a way that natural substances cannot.

In this case, the material has an extremely high refrac­tive index and low reflec­tance. The collimator consists of 339 pairs of meta-atoms arranged so that the refractive index concen­trically increases from the outside to the center of the device. “The meta­surface design is unpre­cedented,” said Suzuki, “delivering a much higher performance that should acce­lerate the development of a wide range of appli­cations, including next-generation wireless communi­cations (6G/7G) and even thermal radiation control devices.” (Source: U. Tokyo)

Reference: T. Suzuki et al.: Terahertz metasurface ultra-thin collimator for power enhancement, Opt. Exp. 28, 22165 (2020); DOI: 10.1364/OE.392814

Abstract-Strong and narrowband terahertz radiation from GaAs based pHEMT and terahertz imaging

Se‐Mi Kim, Sung‐Min Hong, Jae‐Hyung Jang,

https://onlinelibrary.wiley.com/doi/abs/10.1002/mop.32525

Strong and narrowband terahertz (THz) radiation is obtained from a GaAs‐based pseudomorphic high‐electron‐mobility transistor (pHEMT). The radiation properties with respect to the bias conditions and operating temperature are extensively characterized. The maximum emission power is measured to be 63 and 278 μW at room temperature and 77 K, respectively. By using the THz radiation from the pHEMT, a metal object hidden in cloth was successfully imaged.

LUNA BLOG-Time-Domain Terahertz Sensing Does a Better Job Measuring Critical Product Parameters in Medical Tubing

https://lunainc.com/terahertz-medical-tubing/

As the demand for more complex, precisely controlled medical tubing increases, it is increasingly important to have monitoring methods that can provide the full range of product information necessary for the manufacturers to profitably manufacture and validate their products.

Most high-performance medical tubing products are produced by extrusion processes. A hopper of raw polymer pellets feeds into a heater element to melt the material to a liquid form. The liquid polymer is then forced, using a threaded screw, through a die to create the tubing.

The formed tube is kept at a constant extrusion rate and tension, while either passing into a vacuum sizing chamber or with pressurized air pumped into the lumen space, to prevent the still hot low-strength tubing walls from collapsing. The product dimensions are set at this step. The product is typically passed next through a cooling bath. This process is used to create both single layer and multilayer tubing products.

Typical monitoring of the critical product parameters – single and multilayer wall thickness, concentricity, outside diameter (OD) and inside diameter (ID) – is performed by a combination of laser gauges for dimensions and ultrasound for wall thickness measurements.

Ideally, the closer the measurements are made to the extruder, the more responsive the whole system can operate and quickly correct for variations in product.

However, ultrasound measurements require contact with the sample through a couplant. The water in the downstream cooling tanks functions well for this purpose. However, ultrasonic methods can only measure the contact surface; measurement on the opposite tubing wall is not possible without adding more sensors. Laser systems, outside of the cooling tank, are combined with the ultrasound thickness results to provide dimensional measurements.

An ideal sensor would measure all the critical product parameters with better precision, provide simultaneous multilayer measurements (especially for thinner layers and smaller diameter products), be non-contact, have a very fast measurement rate and be completely safe.

A Time-Domain Terahertz Sensor can make very fast and high-precision measurements of these parameters with a single non-contact reflection sensor unit. The measurement concept is like ultrasound while operating in air and other locations ultrasound cannot.

A Terahertz (THz) sensor emits a very narrow completely safe low-energy pulse, which travels through air. Therefore, the probe is non-contact and operates with long standoff distances (25mm, 75mm or 150mm). All materials used for tubing and catheter coatings are transparent to THz.

The emitted THz pulse will reflect off interfaces in the sample, such as the air/outer wall and the internal interfaces between materials in a multilayer wall. The Time-of-Flight (ToF) between the reflections is measured, and the layer thicknesses are calculated from these values.

Measurements are collected at a rate of up to 1000 Hz. The THz beam spot size is approximately 2 mm. Measurement precision as high as ±0.5 micron has been obtained.

To learn more about a better on-line measuring and control solution, read our Tubing THz Applications Note now. 

Abstract-Ageing Condition Determination of Bonded Joints by Terahertz Spectroscopy

Jochen Taiber, Martin Kahlmeyer, Andreas Winkel, Eva-Maria Stübling, Fatima Taleb, Mikhail Mikerov, Stefan Sommer, Stefan Böhm, Martin Koch

https://www.springerprofessional.de/en/ageing-condition-determination-of-bonded-joints-by-terahertz-spe/18206724

The understanding of ageing processes in the field of adhesion technology is of utmost importance for long-term durable bonded joints. Environmental factors such as moisture, heat and UV radiation negatively affect the characteristics of adherends, adhesives and their interfaces and thus the overall bond performance over time. However, the evaluation of the precise ageing condition of adhesive joints remains challenging by means of well-established non-destructive testing (NDT) methods like shearography or thermography. Recently, it has been shown that terahertz (THz) time-domain spectroscopy is well suited as an NDT approach to study adhesive bonds. Specialized data extraction schemes enable the contact-free determination of the refractive index and the absorption coefficient from such measurements. The presented work wants to give an overview on the developments in the application of THz spectroscopy for the ageing condition determination of bonded joints, including the correlation between THz refractive index/absorption and the physical, chemical and mechanical property changes of adherends and adhesives due to ageing, the determination of THz specific values of adhesive joints by means of a reflection setup, the suitability of peak-to-peak amplitude evaluation, and THz imaging

Abstract-Metasurfaces for Terahertz Wavefront Modulation: a Review

Jingwen He, Tao Dong, Baihong Chi, Yan Zhang,

https://link.springer.com/article/10.1007/s10762-020-00677-3

Metasurface is an artificial material composed of a series of subwavelength structure units and has unique electromagnetic characteristics. Based on the ability of manipulating the phase, amplitude, and polarization of electromagnetic wave, various kinds of metasurfaces are designed to realize wavefront manipulations, such as beam focusing, beam steering, vector beams generating, and holographic imaging. This paper reviews the design methods of metasurfaces for wavefront modulation and evolution of the metasurfaces designed for wavefront manipulation in the terahertz (THz) region. The metasurfaces can be divided into two categories: passive and active metasurfaces. For the passive metasurfaces, the single-functional metasurfaces, multifunctional metasurfaces, and high diffraction efficient metasurfaces designed for various THz wavefront shaping, such as focusing, imaging, and special beams generating, are reviewed. For the active metasurfaces, the metasurfaces with fixed structure and all-optical metasurfaces without fixed structure for THz wavefront modulation are summarized. Furthermore, a comparison on the performance of different kinds of metasurfaces for THz wavefront modulation is presented and the development direction and challenges of the THz wavefront modulation metasurfaces in the future are discussed.

Abstract-Efficient Wide-Band Large-Angle Refraction and Splitting of a Terahertz Beam by Low-Index 3D-Printed Bilayer Metagratings

Xipu Dong, Jierong Cheng, Fei Fan, Xianghui Wang, and Shengjiang Chang

https://journals.aps.org/prapplied/abstract/10.1103/PhysRevApplied.14.014064

Near-perfect anomalous reflection and refraction have been demonstrated using passive lossless metasurfaces and metagratings operating at microwave, infrared, and visible frequencies, while related studies at terahertz frequencies are lacking. Here we propose low-index (with a refractive index of 1.57) 3D-printed dielectric metagratings for efficient wide-band diffraction engineering at low terahertz frequencies. A simplified analytical model reveals that the number of propagating waveguide modes inside the grating is a key factor in diffraction engineering, and is insufficient in a low-index design regardless of the detailed dimensions in a period. Additional waveguide modes are introduced in asymmetric bilayer and trilayer metagratings, providing sufficient degrees of freedom for efficient large-angle anomalous refraction and beam splitting. These metagratings are inherently wide-band, benefiting from low dispersion of the waveguide modes. Three metagratings are designed, 3D printed, and tested experimentally at 0.14 THz for ${70}^{\circ }$ refraction, ${80}^{\circ }$ refraction, and $\pm {70}^{\circ }$ beam splitting. The measured efficiency shows good agreement with the design. The proposed metagratings, with simple structures and large feature sizes, can be easily scaled to applications at higher terahertz frequencies.

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Abstract-Mechanical Terahertz Modulation by Skin‐Like Ultrathin Stretchable Metasurface

Xuanqing Fan, Yuhang Li, Sihong Chen, Yufeng Xing, Taisong Pan

https://www.onlinelibrary.wiley.com/doi/abs/10.1002/smll.202002484?af=R

The modulation of terahertz plays a key role in realizing the tunable terahertz devices. The concept of flexible and stretchable electronics provides the possibility to dynamically modulate the terahertz with mechanical strain rather than additional electrical components. Here, the mechanical modulation of the terahertz transmission with a freestanding, skin‐like, and highly stretchable metasurface is experimentally illustrated. The stretchable metasurface is fabricated by merely constructing an Al/PI mesh film consisting of serpentine‐like unit cells, with total thickness of only 7 µm. With the flexibility realized by the extremely small thickness, the metasurface can be stretched, bended, and twisted, which provides the possibility to modulate terahertz transmission properties by the mechanical deformation of the metasurface. The terahertz time domain spectroscopy results indicate that the stretchable metasurface shows the band‐stop frequency selective effect and the transmission of the terahertz wave can be modulated from 0.15 to 0.5 with applied external tensile strains up to 28%, while only 3.4% of the shift of the resonance frequency is observed. The mechanisms of the metasurface and the relation between the modulation effect and the structural mesh parameters are also discussed with the electromagnetic simulations and the LC equivalent circuit model.

Abstract-Demonstration of photonics-aided terahertz wireless transmission system with using silicon photonics circuit

Sang-Rok Moon, Seungjun Han, Sanghwa Yoo, Heuk Park, Won-Kyoung Lee, Joon Ki Lee, Jongwoo Park, Kyoungsik Yu, Seung-Hyun Cho, and Joonyoung Kim

Experimental setup of the THz wireless communication system using silicon photonics circuit (SPC).

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-28-16-23397

We experimentally demonstrate the use of silicon photonics circuit (SPC) in the simple and cost-effective photonics-aided Terahertz (THz) wireless transmission system. We perform theoretical investigation (with experimental confirmation) to understand that the system performance is more sensitive to the free space path loss (FSPL) at the THz wireless link than the SPC’s insertion loss. The SPC, we design and fabricate, combines two incident optical carriers at different wavelengths and modulates one of two optical carriers with data to transfer, consequently reducing the system footprint that is indeed one of the key challenges that must be tackled for better practicability of the THz communication system. We perform experimental verification to show the feasibility of 40 Gb/s non-return-to-zero (NRZ) on-off-keying (OOK) signal transmission over 1.4 m wireless link for possibly its application in short-reach indoor wireless communication systems utilizing (sub-)THz frequency band such as, e.g., indoor WiFi, distributed antenna/radio systems, rack-to-rack data delivery, etc. The SPC could be further integrated with various photonic elements such as semiconductor optical amplifiers, laser diodes, and photo-mixers, which will enable the path towards all-photonic THz-wave synthesizers.

© 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Abstract-Observation of terahertz-induced magnetooscillations in graphene

Erwin Mönch, Denis A. Bandurin, Ivan A. Dmitriev, Isabelle Y. Phinney, Ivan Yahniuk, Takashi Taniguchi, Kenji Watanabe, Pablo Jarillo-Herrero, Sergey D. Ganichev

https://pubs.acs.org/doi/pdf/10.1021/acs.nanolett.0c01918#

When high-frequency radiation is incident upon graphene subjected to a perpendicular magnetic field, graphene absorbs incident photons by allowing transitions between nearest LLs that follow strict selection rules dictated by angular momentum conservation. Here we show a qualitative deviation from this behavior in high-quality graphene devices exposed to terahertz (THz) radiation. We demonstrate the emergence of a pronounced THz-driven photoresponse, which exhibits low-field magnetooscillations governed by the ratio of the frequency of the incoming radiation and the quasiclassical cyclotron frequency. We analyze the modifications of generated photovoltage with the radiation frequency and carrier density and demonstrate that the observed photoresponse shares a common origin with microwave-induced resistance oscillations previously observed in GaAs-based heterostructures, yet in graphene, it appears at much higher frequencies and persists above liquid nitrogen temperatures. Our observations expand the family of radiation-driven phenomena in graphene, paving the way for future studies of nonequilibrium electron transport.

Abstract-The terahertz metamaterials for sensitive biosensors in the detection of ethanol solutions

Author links open overlay panelFuyu Li, Ke He, Tingting Tang, Yinghui Mao, Rui Wang, Chaoyang Li, Jian Shen,

                                               

https://www.sciencedirect.com/science/article/abs/pii/S0030401820307045 

Metamaterials have attracted much attention due to their subwavelength characteristics, especially in the field of unlabeled refractive index sensing. Because biomolecular molecules have special biological fingerprint spectra in terahertz band, high sensitivity sensor components can be realized by using the special electromagnetic response of metamaterials. In this paper, a novel biosensor based on electromagnetic induced reflection is designed. We find that the asymmetrically fractured double-ring resonator can effectively enhance the fano-resonance of electromagnetic induction reflection, where the resonance position occurs at 1.57 THz. Oscillating Lorentz model shows that when the resonant detuning continues to increase, the bright mode and the dark mode are strongly coupled. When the light mode decreases, the radiation loss also decreases, which induces the decrease of resonance ability. The sensitivity of pure ethanol solution (analyte) under  coating thickness is 103.7 GHz/RIU, 107.1 GHz/RIU and 112.05 GHz/RIU, respectively. The sensitivity and full width at half maximum (FWHM) of the sensor are studied from the perspectives of analyte concentration, thickness, and proportion, respectively. The results show the great potential of electromagnetic metamaterials as sensitive sensors in biological solution detection.