Ultrawide-band long-wavelength p-i-n photodetectors

We compare different designs for very high-speed (millimeter-wave) long-wavelength photodetectors, different materials for such detectors, and different ways of characterizing the speed of these devices. Experimental results are given, showing high-speed response with bandwidths beyond 50 GHz, impulse responses less than 10 ps, and detection sensitivities to 0.1 fJ in packaged devices. Discussed is the inherent bandwidth-efficiency limit in conventional p-i-n detectors, which is then compared to theoretical and experimental results for waveguide-geometry detectors.