Optimization of substrate-lens-coupled CMOS field-effect transistor detectors for 250 GHz by pixel binning technique

This paper reports on the optimization of the response characteristics of a substrate lens-coupled detector for 250 GHz. The 3x3 array of detectors has been implemented using 180-nm CMOS technology. Each pixel comprises a circular-slot-antenna-coupled MOSFET detector that can be individually controlled and monitored. Such implementation allows monitoring the power distribution among detectors as well as applying a pixel-binning technique. Our experiments demonstrate that the binned detector exhibits a minimum optical noise equivalent power as low as 25 pW/$\sqrt{Hz}$ at the central frequency. This performance is comparable with that of a individual detector; however, the binned detector has wider angular characteristics and improved modulation bandwidth. Furthermore, the detector array provides information on the focus spot size and can be used for beam monitoring