Electromagnetic diffraction and bidirectional plasmon launching in partially gated 2d systems

TL;DR

This paper provides an exact analytical solution for electromagnetic scattering in partially gated 2D electron systems, revealing how gate edges act as plasmonic couplers that generate bidirectional plasmons with enhanced electric fields.

Contribution

It introduces an exact Wiener-Hopf solution for electromagnetic scattering in partially gated 2DES, advancing understanding beyond previous numerical approaches.

Findings

Edge acts as a plasmonic coupler launching bidirectional plasmons.

Electric fields near the gate edge are significantly enhanced.

Amplitude of ungated plasmons can surpass gated ones depending on reactance.

Abstract

Partially gated two-dimensional electron systems (2DES) represent the basic building block of prospective optoelectronic devices, including electromagnetic detectors and sources. At the same time, the electrodynamic properties of such structures have been addressed only with numerical simulations. Here, we provide an exact solution of electromagnetic scattering problem at a partially gated 2DES using the Wiener-Hopf technique. We find that incident p-polarized field is enhanced in immediate vicinity of gate edge. The edge acts as a plasmonic coupler that launches bidirectional (gated and ungated) plasmons in weakly-dissipative 2DES with impedance of inductive type. Electric fields in these waves markedly exceeds the incident field, especially in the limit of small gate-2DES separation. The amplitude of the ungated wave exceeds that of gated for 2DES reactance above the free-space impedance. Both amplitudes are maximized for the 2DES reactance of the order of free space impedance timed by the ratio of free space wavelength and gate-2DES separation.