Optically-Induced Circular Currents and Giant Inverse Faraday Effect in 2D Electron Liquid for Tunable Absorption of THz radiation

S.O. Potashin, V. Yu. Kachorovskii, M. Shur
Rensselaer Polytechnic Institute,
United States

Keywords: terahertz technology, plasmonics, inverse Faraday effect, tunable absorber

Summary:

We describe and analyze a tunable resonant absorber and modulator of electromagnetic radiation using arrays of nanospheres or nanorings in the vicinity of (or embedded into) a gated two-dimensional electron liquid (2DEL). A circularly polarized electromagnetic wave impinging on the nanospheres creates a system of rotating dipoles inducing circular plasmonic modes (twisted plasmons) in the 2DEL. Rectification of these plasmonic waves due to the 2DEL hydrodynamic nonlinearities leads to helicity-sensitive circular DC current, and consequently, to a magnetic moment. If the nanospheres form a 2D crystal the entire high-mobility 2DEL experiences a resonant circular plasmonic excitation resulting in giant rectified resonant DC current oscillating in space. Since the resonant plasma wave frequency is tunable by the gate voltage and/or by an external magnetic field such a system can be used for the optical tunable magnetization of the 2DEL systems. Our estimates show that these an external magnetic field such a system can be used for the optical tunable magnetization of the 2DEL systems. Our estimates show that these effects could be observed in Si, GaN, InGaAs, and p-diamond materials systems enabling many applications in the terahertz frequency range even at room temperature.