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

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• Optoelectronics
• Photonics
• Plasmonics
• 2-dimensional systems
• Semiconductors
• Two-dimensional electron system
• Electromagnetic wave theory
• Light scattering