Plasmonic Helicity‐Driven Detector of Terahertz Radiation

A theory of the helicity-driven plasmonic dc response of a gated two-dimensional electron gas to terahertz (THz) radiation is developed. A general diagram of a plasmonic detector operating in different regimes is found and analytical equations describing all these regimes are derived. It is demonstrated that the helicity-sensitive part of the response dramatically increases in the vicinity of the plasmonic resonances and oscillates with the phase shift between the excitation signals on the source and drain. The resonance line shape is an asymmetric function of the frequency deviation from the resonance. In contrast, the helicity-insensitive part of the response is symmetrical. These properties yield significant advantage for using plasmonic detectors as helicity-sensitive THz and far infrared spectrometers and interferometers.