Ultra Wide-Band Long Wavelength PIN Photodetectors.

We compare different designs for very-high-speed 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 PIN detectors, which is then compared to theoretical and experimental results for waveguide-geometry detectors.