Abstract-All-metal terahertz metamaterial biosensor for protein detection

 

Gangqi Wang, Fengjie Zhu, Tingting Lang, Jianjun Liu, Zhi Hong,  Jianyuan Qin 

https://nanoscalereslett.springeropen.com/articles/10.1186/s11671-021-03566-3

In this paper, a terahertz (THz) biosensor based on all-metal metamaterial is theoretically investigated and experimentally verified. This THz metamaterial biosensor uses stainless steel materials that are manufactured via laser-drilling technology. The simulation results show that the maximum refractive index sensitivity and the figure of merit of this metamaterial sensor are 294.95 GHz/RIU and 4.03, respectively. Then, bovine serum albumin was chosen as the detection substance to assess this biosensor’s effectiveness. The experiment results show that the detection sensitivity is 72.81 GHz/(ng/mm2) and the limit of detection is 0.035 mg/mL. This THz metamaterial biosensor is simple, cost-effective, easy to fabricate, and has great potential in various biosensing applications.

Abstract-Tunable terahertz metamaterial absorber based on electricity and light modulation modes

Jinfeng Wang, Tingting Lang, Zhi Hong, Tingting Shen, and Gangqi Wang

(a) Schematic view of the proposed tunable THz absorber. (b) Unit cell of the structure with geometrical parameters, the parameters of the absorber are set as p = 80 μm, t = 2 μm, h = 50 μm, b = 0.2 μm, a = 40 μm. The permittivity dispersion (real part: dotted line and imaginary part: solid line) of doped Si in the different layer under the pump fluence of 200 μJ/cm2 is shown on the middle.

https://www.osapublishing.org/ome/abstract.cfm?uri=ome-10-9-2262

In this paper, a metamaterial absorber that achieved absorption tuning by electricity and light control has been proposed in the terahertz (THz) regime. The THz absorber exhibits an absorbance of 97.5% at a resonant frequency of 0.245 THz. First, we simulated the absorption spectra under different structural parameters. Then the absorption characteristics are analyzed under different Fermi energies and pump fluences. When the Fermi energy changes from 0 to 1 eV, the peak absorbance decreases from 97.5% to 56.2%. As the fluence of the pump beam increases from 0 to 100 µJ/cm2, the peak absorbance decreases from 97.5% to 42.8%. The amplitude modulation depth T of our designed absorber is approximately 0.55. Electric and magnetic resonances are proposed in this article, which allows for nearly perfect absorption. Finally, the absorption for both transverse electric and transverse magnetic modes were investigated under different incident angles, from 0° to 75° with a step-width of 15°. The absorber can be potentially applied to THz detection, imaging, and sensing.

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

Abstract-Bessel-like beam generated by an axicon based on parallel-plate waveguides

Tingting Shen, Tingting Lang, Mengru Wu, and Zhanghua Han

https://www.osapublishing.org/ao/abstract.cfm?uri=ao-57-21-6174

The axicon is the simplest and most effective optical element for generating the zero-order Bessel-like beam. The zero-order Bessel-like beam, which has the characteristics of small spot size, high brightness, good direction, and large collimation distance, can be applied to optical micromanipulation and power transmission. In this paper, we proposed and designed a structure for phase manipulation based on parallel-plate waveguides that can be used to realize the functionality of the axicon in the terahertz (THz) region. Meanwhile, we characterized the influence of the cone angle of the axicon and the waist radius of the incident Gaussian beam on the generated zero-order Bessel-like beam by simulation. The planar structure, consisting of a parallel stack of thin copper plates, can be easily fabricated to fulfill the phase requirement to realize the zero-order Bessel-like beam and also can be utilized in THz imaging systems, THz sensing systems, THz communication systems, etc.

© 2018 Optical Society of America

Abstract-Simultaneous measurement of refractive index and temperature based on all-dielectric metasurface

Jie Hu, Tingting Lang, and Guo-hua Shi

https://www.osapublishing.org/oe/abstract.cfm?uri=oe-25-13-15241

In this paper, a novel kind of sensors for simultaneous measurement of refractive index and temperature based on all-dielectric metasurfaces is proposed. The metasurfaces are constructed by an array of silicon nanoblocks on top of the bulk fused silica substrate. We used three-dimensional full wave electromagnetic field simulation by finite integral method to accurately calculate the transmission spectrum of the metasurfaces. Two transmission dips corresponding to the electric and magnetic resonances are observed. Both dips shift as the ambient refractive index or the temperature changes. Simulation results show that the sensing sensitivities of two dips to the refractive index are 243.44 nm/RIU and 159.43 nm/RIU, respectively, while the sensitivities to the temperature are 50.47 pm/°C and 75.20 pm/°C, respectively. After introducing four holes into each silicon nanoblock, the electromagnetic field overlap in the surrounding medium can be further promoted, and the sensitivities to the refractive index increase to 306.71 nm/RIU and 204.27 nm/RIU, respectively. Our proposed sensors have advantages of polarization insensitive, small size, and low loss, which offer them high potential applications in physical, biological and chemical sensing fields.

© 2017 Optical Society of America