Design and Performance of a Room-Temperature Terahertz Detection Array for Real-Time Imaging

A simple mass producible detection array for terahertz radiation has been designed and fabricated. The 1 mm times 1 mm pixels consist of a 0.5 mm times 0.5 mm thin-film absorber on a membrane, supported by 0.28-mm-wide silicon separation beams. Thermopiles are used to measure the temperature increase of the absorber. The 5 ms thermal time constant of the detector, together with the noise equivalent power of 1 nW/Hz^1/2, enables real-time imaging at 50 frames/s with a signal-to-noise ratio of 10 for an optical intensity of 30 muW/cm².     

Terahertz imaging with bow-tie InGaAs-based diode with broken symmetry

A silicon-lens coupled bow-tie InGaAs-based diode with broken symmetry is demonstrated for terahertz imaging applications below 1 THz at room temperature. Transient features and the dynamic range of the bow-tie InGaAs-based sensor are explored experimentally, proving the possibility to use the device in real-time imaging systems. Response time is found to be less than 7 ns, responsivity of 0.1 mA/W, and noise equivalent power of 5.8 nW/radicHz.     

Field Effect Transistors for Terahertz Detection: Physics and First Imaging Applications

Resonant frequencies of the two-dimensional plasma in FETs increase with the reduction of the channel dimensions and can reach the THz range for sub-micron gate lengths. Nonlinear properties of the electron plasma in the transistor channel can be used for the detection and mixing of THz frequencies. At cryogenic temperatures resonant and gate voltage tunable detection related to plasma waves resonances is observed. At room temperature, when plasma oscillations are overdamped, the FET can operate as an efficient broadband THz detector. We present the main theoretical and experimental results on THz detection by FETs in the context of their possible application for THz imaging.     

Waveguide-based calorimeter for terahertz frequency range

A calorimeter for absolute power measurements within the 0.1- 30 THz frequency range is presented and the calibration factor is estimated. Innovations in the design have allowed simplification of direct reading of incident microwave power.     

Field Effect Transistors for Terahertz Detection and Emission

Resonant frequencies of the two-dimensional plasma in field effect transistors (FETs) increase with the reduction of the channel dimensions and can reach the Terahertz (THz) range. Nonlinear properties of the plasma/electron gas in the transistor channel can be used for the rectification and detection of THz radiation. The excitation of plasma waves by sub-THz and THz radiation was demonstrated for short gate transistors at cryogenic temperatures. At room temperature plasma oscillations are usually overdamped, but the FETs can still operate as efficient broadband rectifiers/detectors in the THz range. We present a few recent experimental results on THz detection by FETs showing some new ways of improvement of FETs for THz imaging at room temperature as well as the new physical phenomena like detection in quantizing magnetic fields. We also demonstrate THz emission properties of GaN based FETs.