Noise characterization of patch antenna THz photodetectors

Current noise fluctuations have been investigated in terahertz (THz) quantum well photodetectors embedded in antenna-coupled photonic architectures and compared with standard substrate-coupled mesa detectors. The noise measurements give a value of the photoconductive gain that is in excellent agreement with that extracted from previous responsivity calibrations. Moreover, our results confirm that the noise equivalent power (NEP) of the antenna-coupled devices is of the order of 0.2 pW/Hz0.5. This low NEP value and the wide band frequency response (∼GHz) of the detectors are ideal figures for the development of heterodyne receivers that are, at present, a valuable technological solution to overcome the current limitation of THz sensors.