研究目的
Investigating the sensitivity of a GaAs plasmonic THz detector over a wide range of sub-THz frequencies and exploring the optimization capabilities of the detector frequency response.
研究成果
The frequency response of the detector is greatly affected by the interference of electromagnetic waves inside the substrate. By varying substrate thickness, detector sensitivity can be optimized for a specified operating frequency within 60–700 GHz range. Mounting the detector on a hemispherical silicon lens can achieve considerable suppression of the interference within the substrate, resulting in a more even frequency response with insignificant fluctuation.
研究不足
The study was limited to the frequency range of 65–384 and 530–710 GHz. The effect of THz light interference within the substrate could not be completely eliminated without the use of a specially designed silicon lens.
1：Experimental Design and Method Selection:
The study involved measuring the frequency response of detector samples at room temperature in a quasi-optical setup. A set of backward-wave oscillator (BWO) sources was used to generate a continuous-wave (CW) signal in 65–384 and 530–710 GHz frequency bands. The power level of the radiation incident on the sample was monitored with a calibrated pyroelectric detector.
2：Sample Selection and Data Sources:
The detector was fabricated from GaAs/AlGaAs heterostructure with embedded two-dimensional electron system (2DES) grown on a GaAs substrate. The substrate thickness of each detector sample was adjusted by mechanical grinding.
3：List of Experimental Equipment and Materials:
BWO sources, quasi-optical Fabry–Perot resonator, pyroelectric detector, biconvex TPX lens, polarizer, lock-in amplifier, optical chopper.
4：Experimental Procedures and Operational Workflow:
The radiation emitted from the output horn antenna of the BWO was collimated to form a parallel beam. The polarizer ensured that the E-field component of the irradiance incident on the detector matched the detector preferred orientation. The detector output voltage was measured with a lock-in amplifier in sync with the chopper.
5：Data Analysis Methods:
The measured frequency of each peak was plotted against its expected number, N, for every substrate thickness under consideration. The slopes of the fitted lines were plotted as a function of parameter 1/d.
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