Long-wavelength infrared photovoltaic heterodyne receivers using patch-antenna quantum cascade detectors

Quantum cascade detectors (QCDs) are unipolar infrared devices where the transport of the photoexcited carriers takes place through confined electronic states, without an applied bias. In this photovoltaic mode, the detector's noise is not dominated by a dark shot noise process, and therefore, performances are less degraded at high temperature with respect to photoconductive detectors. This work describes a 9 μm QCD embedded into a patch-antenna metamaterial, which operates with state-of-the-art performances. The metamaterial gathers photons on a collection area, Acoll, much larger than the geometrical area of the detector, improving the signal to noise ratio up to room temperature. The background-limited detectivity at 83 K is 5.5 × 1010 cm Hz1/2 W−1, while at room temperature, the responsivity is 50 mA/W at 0 V bias. A patch antenna QCD is an ideal receiver for a heterodyne detection setup, where a signal at a frequency of 1.4 GHz and T = 295 K is reported as demonstration of uncooled 9 μm photovoltaic receivers with a GHz electrical bandwidth. These findings guide the research toward uncooled IR quantum limited detection.