FIELD OF THE DISCLOSURE

The present disclosure relates to a receiver for electromagnetic radiation in a terahertz (THz) portion of the spectrum and more specifically to a tunable THz detector.

BACKGROUND

Terahertz radiation is generally considered as occupying the portion (i.e., band) of the spectrum from 0.3 to 30 THz, having wavelengths in the range of 1 millimeter (mm) to 0.01 mm. Because this band lies between microwave and infrared it may share properties of each. Transmission range in this band is limited by atmospheric absorption and technology development for transmission and reception has been slow. Interest has grown in time, however, because of advantages associated with this band. For example, THz radiation may be able to penetrate a wide variety of materials while lacking the energy to cause damage (e.g., harm to humans). Communication in this band may also support extremely high bandwidths. The applications for this band will be based on devices, such as a THz detector.

SUMMARY

In at least one aspect, the present disclosure generally describes a terahertz detector circuit that includes a high electron mobility transistor (HEMT) and a gate driver. The HEMT includes a two-dimensional electron gas (2DEG) at a heterojunction between a first heterojunction layer and a second heterojunction layer. The HEMT also includes a plurality of gate terminals. The plurality of gate terminals are disposed on a trace layer that is proximate to (e.g., in an adjacent layer to) the 2DEG. For example, the plurality of gate terminals can be disposed on a trace layer with the first heterojunction layer between the trace layer and the 2DEG. Additionally, the plurality of gate terminals can be spaced apart and span at least a portion of (e.g., an entire length or width of) the 2DEG. The gate driver is configured to apply signals to the plurality of gate terminals according to a tuning configuration in order to generate a gate-induced modulation pattern in the 2DEG that increases a detection sensitivity for a particular terahertz signal.

In another aspect, the present disclosure generally describes a terahertz detector array that includes a plurality of HEMTs, a gate driver circuit and a sensing readout circuit. Each HEMT in the plurality of HEMTs includes a 2DEG at a heterojunction between a first heterojunction layer and a second heterojunction layer. Additionally, each HEMT includes a plurality of gate terminals disposed on a trace layer proximate to the 2DEG. For example, the plurality of gate terminals can be disposed on the trace layer with the first heterojunction layer between the trace layer and the 2DEG. Additionally, the plurality of gate terminals can be spaced apart and span at least a portion of the 2DEG. The gate driver circuit is configured to apply signals to the plurality of gate terminals of each HEMT according to a tuning configuration in order to generate a gate-induced modulation pattern in the 2DEG. The gate-induced modulation pattern increases a detection sensitivity for a particular terahertz signal. The sensing and readout circuit is configured to receive detection signals from each HEMT in response to the particular terahertz signal and to generate an output (e.g., THz image, Multi-spectral THz image) based on the detection signals.

In another aspect, the present disclosure generally describes a method for detecting THz radiation. The method includes applying a first set of gate signals to a plurality of gate terminals that are spatially coupled to a two-dimensional electron gas (2DEG) to generate a first gate-induced modulation pattern in the 2DEG based on the first set of gate signals. The method further includes receiving THz radiation at the 2DEG, the THz radiation including frequency components that generate signal-induced modulation patterns in the 2DEG. The method further includes detecting a first frequency component of the THz radiation that generates a first signal-induced modulation pattern that substantially matches the first gate-induced modulation pattern.

In a possible implementation of the method, the detection of the THz radiation can be tuned by applying a second set of gate signals to the plurality of gate terminals (i.e., instead of the first set of gate signals) to generate a second gate-induced modulation pattern in the 2DEG based on the second set of gate signals, and detecting a second frequency component of the THz radiation that generates a second signal-induced modulation pattern that substantially matches the second gate-induced modulation pattern.

The foregoing illustrative summary, as well as other exemplary objectives and/or advantages of the disclosure, and the manner in which the same are accomplished, are further explained within the following detailed description and its accompanying drawings.

