Terahertz Metamaterial Optoelectronic Modulators With GHz Reconfiguration Speed
Abdullah M. Zaman, Yuezhen Lu, Xavier Romain, Nikita W. Almond, Oliver J. Burton, Jack Alexander-Webber, Stephan Hofmann, Thomas A. Mitchell, J. Griffiths, Harvey E. Beere, D. A. Ritchie, Riccardo Degl’Innocenti
Abstract
All-electronicultrafast control of terahertz radiation is demonstrated in integrated metamaterial/graphene devices. By electrostatic gating the graphene conductivity, the overall optical response of the incident terahertz <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$E$</tex-math></inline-formula> -field is modified. Depending on the configuration, amplitude, phase, and polarization of terahertz radiation could be modulated with GHz range of reconfiguration speed. An extinction ratio of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$>$</tex-math></inline-formula> 7.6 dB in amplitude is achieved at the resonant frequency of 0.75 THz. Additionally, a relative phase shift of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$>\!\!17.4^\circ$</tex-math></inline-formula> is observed around a frequency of 0.68 THz. When operating as a polarization modulator, the device has reported an ellipticity change of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\sim 40\%$</tex-math></inline-formula> at a frequency of 0.68 THz and a dynamic rotation of the polarization plane by <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$>\!\!9^\circ$</tex-math></inline-formula> at resonance. The switching capability of the modulators has been investigated all electronically reporting a speed exceeding 3 GHz, only limited by the available instrumentation. Consequently, GHz-speed of modulation can be achieved for frequencies around 0.75 THz. These results represent a breakthrough for all applications where a fast, versatile, and efficient modulation of THz radiation is required, such as in next-generation wireless communication, quantum electronics, and ultrafast imaging.