Terahertz detection and coherent imaging from 0.2 to 4.3 THz with silicon CMOS field-effect transistors

We summarize several lines of investigation of foundry-processed patch-antenna-coupled Si MOSFETs as plasmonic detectors of THz radiation. First, we explore detection at frequencies as high as 4.3 THz, about one hundred times higher than the transit-time-limited cut-off frequency of the devices, searching for the fundamental limits of the detection principle. Then, we address the much-debated issue of enhanced sensitivity by a current bias and conclude that - because of the increased noise - there is no net gain in signal-to-noise ratio. Finally, we simulate operation of a 100×100-pixel heterodyne camera, working with a few detectors of a focal-plane array and quasi-optical coupling of the local-oscillator radiation, and show that real-time operation of a camera should be possible with a dynamic range of 30 dB for a quarter-milliwatt local-oscillator power.