Optically controlled narrowband terahertz switcher based on graphene
doi:10.3788/CO.20181102.0166
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摘要:本文提出了一种光控太赫兹开关，该开关采用覆盖单层石墨烯的十字金属谐振器超表面。利用石墨烯表面电导率模型和有限元法计算了这种复合结构的光谱特性。模拟结果表明，在0.2 W/mm 2的光泵浦后，传输谱（调制深度为36.8%， Q-因子为250）出现了窄带共振衰减现象。另外，这种衰减的调制深度可以通过改变泵浦强度微调节。因此，光学可调谐太赫兹开关的设计将有助于太赫兹通信应用的功能组件开发。Abstract:This paper proposes an optically controlled terahertz switcher based on cross-shaped metal resonators metasurface covered by monolayer graphene. The spectral characteristics of proposed composite structure were calculated using the surface conductivity model of graphene and the finite element method. The modeling demonstrated the appearance of a narrowband resonant dip in the transmission spectrum with a modulation depth of 36.8% and a Q-factor of 250 after the optical pump intensity achieving to 0.2 W/mm 2. In addition, the modulation depth of such a dip can be slightly tuned by varying value of the pump intensity. Thus, the design of the optically tunable terahertz switcher may contribute to the development of functional components for terahertz communication applications.
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Key words:
- terahertz/
- graphene/
- optical switching devices
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Figure 1.Spectrum of real(a) and imaginary(b) parts of normalized conductivity for single layer graphene at various pumping intensities. Real(c) and imaginary(d) parts of normalized conductivity as function of pumping intensity at various frequencies
Figure 2.Schematic of the unit cell geometry under consideration: the periodic cross-shaped aluminum/graphene arrays with widthK, lengthLand periodG. The arrays are located on a PET substrate with thicknessd. The incident EM wave is TE polarized with the electric fields along theyaxis. The plane wave normally(alongz) impinges on the switcher
Figure 3.Transmission, reflection and absorption spectra of graphene based metamaterial switcher without optical pumping. The polarization of the incident light is along theydirection
Figure 4.Transmission, reflection and absorption spectra of graphene based metamaterial switcher under optical pumping with intensity ofIpump=0.2 W/mm2. The polarization of the incident light is along theydirection
Figure 5.Transmission at 0.271 THz for different optical pumping intensity after turning on the switcher
Figure 6.Electric field distributions from the metal surface of structure at the reflection and absorption peak(0.271 THz) without(a) and with(b) optical pumping(0.2 W/mm2)
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