On-chip near-field terahertz detection based on a two-dimensional electron gas

We report on a high-resolution terahertz (THz) imaging beyond the diffraction limit by using a two-dimensional electron gas (2DEG) in a GaAs/AlGaAs heterostructure. In this imaging device, all components: an aperture, a probe, and a detector are integrated on one GaAs/AlGaAs chip. Calculations based on a finite element method show that the presence of the probe changes the distribution profile of the evanescent field just behind the aperture, enhancing the coupling of the evanescent field to the 2DEG THz detector. THz transmission measurements demonstrate that the present device works as a near-field THz imaging detector. A near-field image of THz cyclotron emission in another 2DEG sample is also presented.