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Sengupta R, Khand H, Sarusi G. THz Metamaterial Sensitivity Enhancement by Reduction of Substrate's Fabry-Pérot Oscillations Using Back Plates as an Optical De-Coupler. ACS APPLIED MATERIALS & INTERFACES 2024; 16:45107-45118. [PMID: 39143036 DOI: 10.1021/acsami.4c06187] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/16/2024]
Abstract
This work presents a new method for the enhancement of sensitivity in Terahertz (THz) spectroscopy on metamaterial (MM) in terms of its resonance frequency shift (ΔF), by attaching the dielectric back plate to the MM's silicon (Si) wafer. The dielectric back plates are designed to minimize the Fresnel reflections at the backside of the substrate, identical to a broadband antireflective (AR) plate tailored for THz. Utilizing broadband AR technology, we demonstrate the concept of decoupling MM resonance from the substrate's Fabry-Pérot (FP) oscillations. This is done by effectively coupling the THz light out of the high-permittivity substrate, resulting in the improved quality factor of the MM resonance and overall plasmonic enhancement on the metasurface. The back plate acts as a surface plasmonic enhancer to the THz MM by increasing the field intensity on the front metasurface, leading to enhancement of dielectric response (MM's ΔF). This makes the MM resonance ultrasensitive to the minor changes of particle size/concentration under test spread on the metasurface, contributing to enhanced resonance ΔF. The plate also makes the Si substrate optically lossless, enabling the full effect of MM resonance shift and increasing the resonance ΔF by 8-fold compared with MM's fabricated on conventional Si substrates. This research is backed-up with system-level CST simulations and experimental THz impedance spectroscopy of the MM. This method and chip structure is CMOS compatible having potential applications for any resonant MM fabricated on a substrate aimed to maximize dielectric sensitivity for biosensing and nanoparticle THz spectroscopy.
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Affiliation(s)
- Rudrarup Sengupta
- Department of Photonics and Electro-Optics Engineering, School of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel
| | - Heena Khand
- Department of Photonics and Electro-Optics Engineering, School of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel
| | - Gabby Sarusi
- Department of Photonics and Electro-Optics Engineering, School of Electrical and Computer Engineering, Ben-Gurion University of the Negev, Beer Sheva 8410501, Israel
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Chern RL, Yang HC, Chang JC. Bound states in the continuum in asymmetric dual-patch metasurfaces. OPTICS EXPRESS 2023; 31:16570-16581. [PMID: 37157733 DOI: 10.1364/oe.487611] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
We investigate the bound states in the continuum (BICs) in dielectric metasurfaces consisting of asymmetric dual rectangular patches in the unit cell of a square lattice. Various types of BICs are identified in the metasurface at normal incidence, associated with very large quality factors and vanishing spectral linewidths. In particular, symmetry-protected (SP) BICs occur when the four patches are fully symmetric, which exhibit antisymmetric field patterns that are decoupled from the symmetric incident waves. By breaking the symmetry of patch geometry, the SP BICs degrade to quasi-BICs that are characterized by Fano resonance. Accidental BICs and Friedrich-Wintgen (FW) BICs occur when the asymmetry is introduced in the upper two patches, while holding the lower two patches symmetric. The accidental BICs occur on isolated bands when the linewidth of either the quadrupole-like mode or LC-like mode vanishes by tuning the upper vertical gap width. The FW BICs appear when the avoided crossing is formed between the dispersion bands of dipole-like and quadrupole-like modes by tuning the lower vertical gap width. At a special asymmetry ratio, the accidental BICs and FW BICs may appear in the same transmittance or dispersion diagram, accompanied with the concurrence of dipole-like, quadrupole-like, and LC-like modes.
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Huang C, Zhang Y, Liang L, Yao H, Qiu F, Liu W. Analysis of graphene-based tunable THz four-band absorption sensors. APPLIED OPTICS 2022; 61:2103-2107. [PMID: 35297903 DOI: 10.1364/ao.447968] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 02/05/2022] [Indexed: 06/14/2023]
Abstract
A novel, to the best of our knowledge, four-band tunable absorber sensor, based on a graphene layer, is presented. The proposed sensor configuration is composed of a single monolayer of graphene placed on top of a SiO2 dielectric substrate, whereas a gold grounding plane is placed beneath the SiO2. In addition, the resonant frequencies of the sensor can be directly controlled by adjusting the Fermi level of graphene, while the absorption rate reaches a value greater than 99% at all resonant peaks. The acquired calculation results of the refractive index sensitivity of our proposed sensor show that the four resonant peaks possess superior sensing characteristics. Additionally, by covering the measured objects with different refractive indices, the acquired results indicate that the sensing performance of the sensor exhibits good linearity. From our analysis, it is concluded that the absorbing sensor exhibits a broad range of potential applications in the biomedical field.
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Wang R, Xu L, Wang J, Sun L, Jiao Y, Meng Y, Chen S, Chang C, Fan C. Electric Fano resonance-based terahertz metasensors. NANOSCALE 2021; 13:18467-18472. [PMID: 34726683 DOI: 10.1039/d1nr04477j] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/28/2023]
Abstract
An ultra-sensitive THz metasensor is presented based on quasi-BIC Fano resonance, which can distinguish extremely dilute concentrations (nM) of solutions. It provides a nondestructive sensing approach for disease prevention and diagnosis. However, the main drawback limiting the performance of THz-based bio-chemical sensors is the weak interaction between the optical field and the analyte, the characteristic scale of which is mismatched with the THz wavelength, leading to low sensitivity. Herein, we present an ultra-sensitive THz metasensor based on an electric Fano resonant metasurface which consists of three gold microrods arranged periodically. The designed electric Fano resonance provides a strong near-field enhancement near the surface of the microstructure, significantly boosting the light-analyte interactions and thus the sensitivity. Such an electric Fano resonance is formed by the interference between a leaky electric dipole resonance and a bound toroidal dipole mode which is a symmetry-protected bound state in the continuum supported by the sub-diffractive periodic system here. Owing to the strong electric fields generated near the interface of our microstructure around the toroidal dipole BIC, the proposed structure can distinguish extremely dilute concentrations (nM) of solutions. Importantly, by controlling the degree of geometrical asymmetry, the BIC-inspired mechanism provides an important and simple tool to engineer and tailor the linewidth and Q-factor of our proposed electric Fano resonance, indicating the ability to realize different biosensors for different optical regimes. Our results open new possibilities to realize a non-destructive and non-contact quantitative inspection of low-concentration solutions, providing a useful sensing approach for disease prevention and diagnosis.
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Affiliation(s)
- Ride Wang
- Innovation Laboratory of Terahertz Biophysics, National Innovation Institute of Defense Technology, Beijing, 100071, China.
| | - Lei Xu
- Advanced Optics and Photonics Laboratory, Department of Engineering, School of Science and Technology, Nottingham Trent University, Nottingham NG11 8NS, UK
| | - Jiayi Wang
- Key Laboratory of Weak-Light Nonlinear Photonics, Ministry of Education, TEDA Institute of Applied Physics and School of Physics, Nankai University, Tianjin 300457, China
| | - Lang Sun
- Innovation Laboratory of Terahertz Biophysics, National Innovation Institute of Defense Technology, Beijing, 100071, China.
| | - Yanan Jiao
- Department of General Surgery, First Medical Center of Chinese PLA General Hospital, Beijing 100853, People's Republic of China
| | - Yuan Meng
- Key Laboratory of Photonics Control Technology of the Ministry of Education, Tsinghua University, China
| | - Shuo Chen
- Innovation Laboratory of Terahertz Biophysics, National Innovation Institute of Defense Technology, Beijing, 100071, China.
| | - Chao Chang
- Innovation Laboratory of Terahertz Biophysics, National Innovation Institute of Defense Technology, Beijing, 100071, China.
- School of Physics, Peking University, Beijing, 100871, China
| | - Chunhai Fan
- School of Chemistry and Chemical Engineering, Shanghai Jiao Tong University, Shanghai, 200240, China.
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Sinev IS, Koshelev K, Liu Z, Rudenko A, Ladutenko K, Shcherbakov A, Sadrieva Z, Baranov M, Itina T, Liu J, Bogdanov AA, Kivshar Y. Observation of Ultrafast Self-Action Effects in Quasi-BIC Resonant Metasurfaces. NANO LETTERS 2021; 21:8848-8855. [PMID: 34633185 DOI: 10.1021/acs.nanolett.1c03257] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
High-index dielectric metasurfaces can support sharp optical resonances enabled by the physics of bound states in the continuum (BICs) often manifested in experiments as quasi-BIC resonances. They provide a way to enhance light-matter interaction at the subwavelength scale bringing novel opportunities for nonlinear nanophotonics. Strong narrow-band field enhancement in quasi-BIC metasurfaces leads to an extreme sensitivity to a change of the refractive index that may limit nonlinear functionalities for the pump intensities beyond the perturbative regime. Here we study ultrafast self-action effects observed in quasi-BIC silicon metasurfaces and demonstrate how they alter the power dependence of the third-harmonic generation efficiency. We study experimentally a transition from the subcubic to supercubic regimes for the generated third-harmonic power driven by a blue-shift of the quasi-BIC in the multiphoton absorption regime. Our results suggest a way to implement ultrafast nonlinear dynamics in high-index resonant dielectric metasurfaces for nonlinear meta-optics beyond the perturbative regime.
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Affiliation(s)
- Ivan S Sinev
- School of Physics and Engineering, ITMO University, St. Petersburg 197101, Russia
| | - Kirill Koshelev
- School of Physics and Engineering, ITMO University, St. Petersburg 197101, Russia
- Nonlinear Physics Center, Research School of Physics, Australian National University, Canberra, ACT 2601, Australia
| | - Zhuojun Liu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, Guangzhou 510275, China
| | - Anton Rudenko
- Arizona Center for Mathematical Sciences and College of Optical Sciences, University of Arizona, Tucson, Arizona 85721, United States
| | - Konstantin Ladutenko
- School of Physics and Engineering, ITMO University, St. Petersburg 197101, Russia
| | - Alexey Shcherbakov
- School of Physics and Engineering, ITMO University, St. Petersburg 197101, Russia
| | - Zarina Sadrieva
- School of Physics and Engineering, ITMO University, St. Petersburg 197101, Russia
| | - Mikhail Baranov
- School of Physics and Engineering, ITMO University, St. Petersburg 197101, Russia
| | - Tatiana Itina
- School of Physics and Engineering, ITMO University, St. Petersburg 197101, Russia
- Laboratoire Hubert Curien, UMR CNRS 5516/UJM/Université de Lyon, Saint-Etienne 42000, France
| | - Jin Liu
- State Key Laboratory of Optoelectronic Materials and Technologies, School of Physics, Sun Yat-sen University, Guangzhou 510275, China
| | - Andrey A Bogdanov
- School of Physics and Engineering, ITMO University, St. Petersburg 197101, Russia
| | - Yuri Kivshar
- School of Physics and Engineering, ITMO University, St. Petersburg 197101, Russia
- Nonlinear Physics Center, Research School of Physics, Australian National University, Canberra, ACT 2601, Australia
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Liu H, Wang P, Wu J, Yan X, Yuan X, Zhang Y, Zhang X. Switchable and Dual-Tunable Multilayered Terahertz Absorber Based on Patterned Graphene and Vanadium Dioxide. MICROMACHINES 2021; 12:mi12060619. [PMID: 34072164 PMCID: PMC8226437 DOI: 10.3390/mi12060619] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/20/2021] [Revised: 05/22/2021] [Accepted: 05/25/2021] [Indexed: 11/16/2022]
Abstract
In this paper, a switchable and dual-tunable terahertz absorber based on patterned graphene and vanadium dioxide is proposed and analyzed. By controlling the Fermi level of graphene and the temperature of vanadium dioxide, the device’s function can be switched and its absorbing properties can be tuned. When the vanadium dioxide is in an insulator state, the device can be switched from near-total reflection (>97%) to ultra-broadband absorption (4.5–10.61 THz) as the Fermi level of graphene changes from 0 to 0.8 eV. When the vanadium dioxide is changed to a metal state, the device can act as a single-band absorber (when the Fermi level of graphene is 0 eV) and a dual-band absorber with peaks of 4.16 THz and 7.3 THz (when the Fermi level of graphene is 0.8 eV). Additionally, the absorber is polarization-insensitive and can maintain a stable high-absorption performance within a 55° incidence angle. The multilayered structure shows great potential for switchable and tunable high-performance terahertz devices.
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Affiliation(s)
- Hongyao Liu
- State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China; (H.L.); (P.W.); (J.W.); (X.Y.); (Y.Z.); x (X.Z.)
- School of Information and Communication Engineering, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Panpan Wang
- State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China; (H.L.); (P.W.); (J.W.); (X.Y.); (Y.Z.); x (X.Z.)
| | - Jiali Wu
- State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China; (H.L.); (P.W.); (J.W.); (X.Y.); (Y.Z.); x (X.Z.)
| | - Xin Yan
- State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China; (H.L.); (P.W.); (J.W.); (X.Y.); (Y.Z.); x (X.Z.)
- Correspondence:
| | - Xueguang Yuan
- State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China; (H.L.); (P.W.); (J.W.); (X.Y.); (Y.Z.); x (X.Z.)
| | - Yangan Zhang
- State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China; (H.L.); (P.W.); (J.W.); (X.Y.); (Y.Z.); x (X.Z.)
| | - Xia Zhang
- State Key Laboratory of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China; (H.L.); (P.W.); (J.W.); (X.Y.); (Y.Z.); x (X.Z.)
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Yan X, Zhang Z, Liang L, Yang M, Wei D, Song X, Zhang H, Lu Y, Liu L, Zhang M, Wang T, Yao J. A multiple mode integrated biosensor based on higher order Fano metamaterials. NANOSCALE 2020; 12:1719-1727. [PMID: 31894802 DOI: 10.1039/c9nr07777d] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A multiple mode integrated biosensor based on higher order Fano metamaterials (FRMMs) is proposed. The frequency shifts (Δf) of x-polarized quadrupolar (Qx), octupolar (Ox), hexadecapolar (Hx), y-polarized quadrupolar (Qy) and octupolar (Oy) Fano resonance modes are integrated to detect the concentration of lung cancer cells. In experiments, the concentrations of lung cancer cells can be distinguished by the shape and distribution of integrated graphics. In addition, an anomalous response in Δf in resonant mode is surprisingly observed. As the cell concentration increases, the Δf at the Qx-dip, Qy-dip and Oy-dip successively experiences an increasing frequency shift stage (IFSS), decreasing frequency shift stage (DFSS) and re-increasing frequency shift stage (RIFSS). The extraordinary DFSS confirmed by single-factor analysis of variance (ANOVA) means an unusual physical phenomenon in metamaterial biosensors. By introducing a new dielectric constant εf, we amend perturbation theory to explain the unusual phenomenon in Δf. With the change of the mode order from Qx to Hx, the εf increases from -2.78 to 0.75, which implies that the negative εf leads to the appearance of the DFSS. As a platform for biosensing, this study opens a new window from the perspective of multiple mode integration.
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Affiliation(s)
- Xin Yan
- School of Opto-Electronic Engineering, Zaozhuang University, Zaozhuang, China.
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Active Switching of Extremely High-Q Fano Resonances Using Vanadium Oxide-Implanted Terahertz Metamaterials. APPLIED SCIENCES-BASEL 2020. [DOI: 10.3390/app10010330] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In this paper, we demonstrate an active switching of extremely high Q-factor Fano resonances using vanadium oxide (VO2)-implanted THz asymmetric double C-shaped metamaterial (MM) structures. The simulation results indicate the highly temperature-sensitive nature of the double Fano resonances that can be switched at very low external thermal pumping (68 °C), which is only slightly higher than room temperature. We employ the surface current and electric field distributions of the structure to analyze the physical mechanism of the observed switching behavior in the thermally excited Fano MMs. More importantly, by optimizing the asymmetric parameter (offset length), the linewidth of the Fano resonance can reach only 0.015 THz and the Q-factor is as high as 98, which is one order of magnitude higher than that of the traditional MMs. The findings of this work would enable a thermally-induced high-Q Fano resonance MMs for ultra-sensitive sensors, modulators, low threshold switching in metadevices.
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Tunable THz Graphene Filter Based on Cross-In-Square-Shaped Resonators Metasurface. PHOTONICS 2019. [DOI: 10.3390/photonics6040119] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The tunable terahertz (THz) Fano-resonant filter based on hybrid metal-graphene metamaterial was proposed. The optical parameters of metasurface with unit cell in the form of a cross-shaped graphene sheet in the center of a square gold ring were simulated by the finite element method using a surface conductivity model of a graphene monolayer. The narrowband modulation of the transmission by varying the Fermi level of the graphene and the position of graphene cross inside the metal ring was demonstrated. Simulation results were well explained theoretically using a three-coupled oscillator model. The proposed device can be used as a narrowband filter in wireless THz communication systems and sensing applications.
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Yang M, Zhang Z, Liang L, Yan X, Wei D, Song X, Zhang H, Lu Y, Wang M, Yao J. Sensitive detection of the concentrations for normal epithelial cells based on Fano resonance metamaterial biosensors in terahertz range. APPLIED OPTICS 2019; 58:6268-6273. [PMID: 31503769 DOI: 10.1364/ao.58.006268] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/17/2023]
Abstract
In this paper, we have cultured normal epithelial cells (HaCaT) as analytes to detect the sensitivity of a biosensor based on Fano resonance metamaterials (FRMMs). The frequency shift Δf of the transmission spectrum was experimentally measured at three different concentrations (0.2×105, 0.5×105, and 5×105 cell/ml) of HaCaT cells. By employing the FRMMs-based biosensor, the detection concentration of HaCaT cells can approximately arrive at 0.2×105 cell/ml; further, the corresponding Δf is 25 GHz, which reaches the measurement limit of the THz-TDS system. Additionally, the increase of HaCaT cell concentration causes a different redshift of Δf from 24-50 GHz, and the maximum of Δf can reach 50 GHz when the HaCaT cell concentration is at 5×105 cell/ml. Similarly, the simulated results show that the Δf depends on the numbers of analytes with a semiball shape and the refractive index of analytes. The theoretical sensitivity was calculated to be 481 GHz/RIU. The proposed FRMMs-based biosensor paves a fascinating platform for biological and biomedical applications and may become a valuable complementary reference for traditional biological research.
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Koshelev K, Lepeshov S, Liu M, Bogdanov A, Kivshar Y. Asymmetric Metasurfaces with High-Q Resonances Governed by Bound States in the Continuum. PHYSICAL REVIEW LETTERS 2018; 121:193903. [PMID: 30468599 DOI: 10.1103/physrevlett.121.193903] [Citation(s) in RCA: 346] [Impact Index Per Article: 57.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/28/2018] [Indexed: 05/20/2023]
Abstract
We reveal that metasurfaces created by seemingly different lattices of (dielectric or metallic) meta-atoms with broken in-plane symmetry can support sharp high-Q resonances arising from a distortion of symmetry-protected bound states in the continuum. We develop a rigorous theory of such asymmetric periodic structures and demonstrate a link between the bound states in the continuum and Fano resonances. Our results suggest the way for smart engineering of resonances in metasurfaces for many applications in nanophotonics and metaoptics.
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Affiliation(s)
- Kirill Koshelev
- Nonlinear Physics Centre, Australian National University, Canberra ACT 2601, Australia
- ITMO University, St. Petersburg 197101, Russia
| | | | - Mingkai Liu
- Nonlinear Physics Centre, Australian National University, Canberra ACT 2601, Australia
| | | | - Yuri Kivshar
- Nonlinear Physics Centre, Australian National University, Canberra ACT 2601, Australia
- ITMO University, St. Petersburg 197101, Russia
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