We present the theory of a field effect transistor (FET) operating as a THz or far infrared detector. We demonstrate that the detected signal is enhanced by orders of magnitudes by using a homodyne detection scheme involving the interference of a weak incoming signal and a strong signal of a local oscillator with the close frequency. We developed a theory valid for the arbitrary relationship between the amplitude of the local oscillator and the gate voltage swing. Remarkably, the response saturates at a high local oscillator intensity at the value which depends on the phase difference between the signals. The observed gain in this regime is over 100, and the predicted maximum gain in this operating regime is on the order of 105. These results show that a FET could be used as a sensitive spectrometer and/or interferometer when exposed to a strong tunable local oscillator signal with the varying frequencies and phases. This regime of the detector operation is very promising for the interferometric and spect...

中文翻译：

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零差相敏太赫兹光谱仪

我们介绍了作为太赫兹或远红外探测器运行的场效应晶体管 (FET) 的理论。我们证明了通过使用零差检测方案，检测到的信号增强了几个数量级，该方案涉及弱输入信号和具有接近频率的本地振荡器的强信号的干扰。我们开发了一个理论，适用于本地振荡器的幅度和栅极电压摆幅之间的任意关系。值得注意的是，响应在高本地振荡器强度下饱和，该值取决于信号之间的相位差。在该状态下观察到的增益超过 100，并且在该运行状态中预测的最大增益约为 105。这些结果表明，当暴露于具有变化频率和相位的强可调谐本地振荡器信号时，FET 可用作灵敏的光谱仪和/或干涉仪。这种探测器操作机制对于干涉测量和光谱测量非常有希望...